diff --git a/globus_sdk/auth/client_types/base.py b/globus_sdk/auth/client_types/base.py
index 07f26d0a..4554ebb7 100644
--- a/globus_sdk/auth/client_types/base.py
+++ b/globus_sdk/auth/client_types/base.py
@@ -360,7 +360,7 @@ class AuthClient(BaseClient):
 
         **Parameters**
 
-            ``response_type``
+            ``response_class``
               Defaults to :class:`OAuthTokenResponse \
               <globus_sdk.auth.token_response.OAuthTokenResponse>`. This is
               used by calls to the oauth2_token endpoint which need to
diff --git a/globus_sdk/auth/client_types/confidential_client.py b/globus_sdk/auth/client_types/confidential_client.py
index 2b00cc3c..573e9207 100644
--- a/globus_sdk/auth/client_types/confidential_client.py
+++ b/globus_sdk/auth/client_types/confidential_client.py
@@ -139,7 +139,7 @@ class ConfidentialAppAuthClient(AuthClient):
             state=state, refresh_tokens=refresh_tokens)
         return self.current_oauth2_flow_manager
 
-    def oauth2_get_dependent_tokens(self, token):
+    def oauth2_get_dependent_tokens(self, token, additional_params=None):
         """
         Does a `Dependent Token Grant
         <https://docs.globus.org/api/auth/reference/#dependent_token_grant_post_v2_oauth2_token>`_
@@ -166,14 +166,23 @@ class ConfidentialAppAuthClient(AuthClient):
           ``token`` (*string*)
             An Access Token as a raw string, being exchanged.
 
+          ``additional_params`` (*dict*)
+            A ``dict`` or ``None``, which specifies additional parameters
+            to include in the request body
+
         :rtype: :class:`OAuthTokenResponse
                 <globus_sdk.auth.token_response.OAuthTokenResponse>`
         """
         self.logger.info('Getting dependent tokens from access token')
-        return self.oauth2_token({
+        self.logger.debug('additional_params={}'.format(additional_params))
+        form_data = {
             'grant_type': 'urn:globus:auth:grant_type:dependent_token',
-            'token': token},
-            response_class=OAuthDependentTokenResponse)
+            'token': token}
+        if additional_params:
+            form_data.update(additional_params)
+
+        return self.oauth2_token(
+            form_data, response_class=OAuthDependentTokenResponse)
 
     def oauth2_token_introspect(self, token, include=None):
         """
diff --git a/globus_sdk/authorizers/client_credentials.py b/globus_sdk/authorizers/client_credentials.py
index 6f82b4ee..d5649942 100644
--- a/globus_sdk/authorizers/client_credentials.py
+++ b/globus_sdk/authorizers/client_credentials.py
@@ -48,8 +48,16 @@ class ClientCredentialsAuthorizer(RenewingAuthorizer):
           POSIX timestamp (i.e. seconds since the epoch)
 
         ``on_refresh`` (*callable*)
-          Will be called as fn(token_data) any time this authorizer
-          fetches a new access_token
+          A callback which is triggered any time this authorizer fetches a new
+          access_token. The ``on_refresh`` callable is invoked on the
+          :class:`OAuthTokenResponse \
+                  <globus_sdk.auth.token_response.OAuthTokenResponse>`
+          object resulting from the token being refreshed.
+          It should take only one argument, the token response object.
+
+          This is useful for implementing storage for Access Tokens, as the
+          ``on_refresh`` callback can be used to update the Access Tokens and
+          their expiration times.
     """
     def __init__(self, confidential_client, scopes,
                  access_token=None, expires_at=None, on_refresh=None):
diff --git a/globus_sdk/authorizers/refresh_token.py b/globus_sdk/authorizers/refresh_token.py
index 6ca6e458..1cd35305 100644
--- a/globus_sdk/authorizers/refresh_token.py
+++ b/globus_sdk/authorizers/refresh_token.py
@@ -43,8 +43,16 @@ class RefreshTokenAuthorizer(RenewingAuthorizer):
           POSIX timestamp (i.e. seconds since the epoch)
 
         ``on_refresh`` (*callable*)
-        Will be called as fn(token_data) any time this authorizer
-        fetches a new access_token
+          A callback which is triggered any time this authorizer fetches a new
+          access_token. The ``on_refresh`` callable is invoked on the
+          :class:`OAuthTokenResponse \
+                  <globus_sdk.auth.token_response.OAuthTokenResponse>`
+          object resulting from the token being refreshed.
+          It should take only one argument, the token response object.
+
+          This is useful for implementing storage for Access Tokens, as the
+          ``on_refresh`` callback can be used to update the Access Tokens and
+          their expiration times.
     """
     def __init__(self, refresh_token, auth_client,
                  access_token=None, expires_at=None, on_refresh=None):
diff --git a/globus_sdk/authorizers/renewing.py b/globus_sdk/authorizers/renewing.py
index 07fe7cd5..e2d711e8 100644
--- a/globus_sdk/authorizers/renewing.py
+++ b/globus_sdk/authorizers/renewing.py
@@ -28,6 +28,28 @@ class RenewingAuthorizer(GlobusAuthorizer):
     To make an authorizer that implements this class implement
     the _get_token_response and _extract_token_data methods for that
     authorization type,
+
+    **Parameters**
+
+        ``access_token`` (*string*)
+          Initial Access Token to use. Used only if ``expires_at`` is also set,
+          otherwise ignored.
+
+        ``expires_at`` (*int*)
+          Expiration time for the starting ``access_token`` expressed as a
+          POSIX timestamp (i.e. seconds since the epoch)
+
+        ``on_refresh`` (*callable*)
+          A callback which is triggered any time this authorizer fetches a new
+          access_token. The ``on_refresh`` callable is invoked on the
+          :class:`OAuthTokenResponse \
+                  <globus_sdk.auth.token_response.OAuthTokenResponse>`
+          object resulting from the token being refreshed.
+          It should take only one argument, the token response object.
+
+          This is useful for implementing storage for Access Tokens, as the
+          ``on_refresh`` callback can be used to update the Access Tokens and
+          their expiration times.
     """
 
     def __init__(self, access_token=None, expires_at=None, on_refresh=None):
@@ -109,9 +131,14 @@ class RenewingAuthorizer(GlobusAuthorizer):
             self.on_refresh(res)
             logger.debug("Invoked on_refresh callback")
 
-    def _check_expiration_time(self):
+    def check_expiration_time(self):
         """
         Check if the expiration timer is done, and renew the token if it is.
+
+        This is called implicitly by ``set_authorization_header``, but you can
+        call it explicitly if you want to ensure that a token gets refreshed.
+        This can be useful in order to get at a new, valid token via the
+        ``on_refresh`` handler.
         """
         logger.debug("RenewingAuthorizer checking expiration time")
         if self.access_token is None or (
@@ -129,7 +156,7 @@ class RenewingAuthorizer(GlobusAuthorizer):
         Once that's done, sets the ``Authorization`` header to
         "Bearer <access_token>"
         """
-        self._check_expiration_time()
+        self.check_expiration_time()
         logger.debug(("Setting RefreshToken Authorization Header:"
                       'Bearer token has hash "{}"')
                      .format(self.access_token_hash))
diff --git a/globus_sdk/base.py b/globus_sdk/base.py
index ec668bcd..8fd51190 100644
--- a/globus_sdk/base.py
+++ b/globus_sdk/base.py
@@ -80,16 +80,16 @@ class BaseClient(object):
                     type(self), self.allowed_authorizer_types,
                     type(authorizer)))
 
-        # defer this default until instantiation time so that logging can
-        # capture the execution of the config load
-        if environment is None:
-            environment = config.get_default_environ()
+        # if an environment was passed, it will be used, but otherwise lookup
+        # the env var -- and in the special case of `production` translate to
+        # `default`, regardless of the source of that value
+        # logs the environment when it isn't `default`
+        self.environment = config.get_globus_environ(inputenv=environment)
 
-        self.environment = environment
         self.authorizer = authorizer
 
         if base_url is None:
-            self.base_url = config.get_service_url(environment, service)
+            self.base_url = config.get_service_url(self.environment, service)
         else:
             self.base_url = base_url
         if base_path is not None:
@@ -104,13 +104,13 @@ class BaseClient(object):
         }
 
         # verify SSL? Usually true
-        self._verify = config.get_ssl_verify(environment)
+        self._verify = config.get_ssl_verify(self.environment)
         # HTTP connection timeout
         # this is passed verbatim to `requests`, and we therefore technically
         # support a tuple for connect/read timeouts, but we don't need to
         # advertise that... Just declare it as an float value
         if http_timeout is None:
-            http_timeout = config.get_http_timeout(environment)
+            http_timeout = config.get_http_timeout(self.environment)
         self._http_timeout = http_timeout
         # handle -1 by passing None to requests
         if self._http_timeout == -1:
diff --git a/globus_sdk/config.py b/globus_sdk/config.py
index d1c7147f..1f5bc364 100644
--- a/globus_sdk/config.py
+++ b/globus_sdk/config.py
@@ -175,17 +175,25 @@ def _bool_cast(value):
     raise ValueError("Invalid config bool")
 
 
-def get_default_environ():
+def get_globus_environ(inputenv=None):
     """
-    Get the default environment to look for in the config, as a string.
+    Get the environment to look for in the config, as a string.
+
     Typically just "default", but it can be overridden with
     `GLOBUS_SDK_ENVIRONMENT` in the shell environment. In that case, any client
     which does not explicitly specify its environment will use this value.
+
+    :param inputenv: An environment which was passed, e.g. to a client
+                     instantiation
     """
-    env = os.environ.get('GLOBUS_SDK_ENVIRONMENT', 'default')
+    if inputenv is None:
+        env = os.environ.get('GLOBUS_SDK_ENVIRONMENT', 'default')
+    else:
+        env = inputenv
+
     if env == 'production':
         env = 'default'
     if env != 'default':
         logger.info(('On lookup, non-default environment: '
-                     'GLOBUS_SDK_ENVIRONMENT={}'.format(env)))
+                     'globus_environment={}'.format(env)))
     return env

diff --git a/tests/unit/test_config.py b/tests/unit/test_config.py
index 7ed9106e..fee2929c 100644
--- a/tests/unit/test_config.py
+++ b/tests/unit/test_config.py
@@ -148,22 +148,35 @@ class ConfigParserTests(CapturedIOTestCase):
         with self.assertRaises(ValueError):
             globus_sdk.config._bool_cast("invalid")
 
-    def test_get_default_environ(self):
+    def test_get_globus_environ(self):
         """
         Confirms returns "default", or the value of GLOBUS_SDK_ENVIRONMENT
         """
-        # default if no environ value exists
-        prev_setting = None
-        if "GLOBUS_SDK_ENVIRONMENT" in os.environ:
-            prev_setting = os.environ["GLOBUS_SDK_ENVIRONMENT"]
+        # mock environ to ensure it gets reset
+        with mock.patch.dict(os.environ):
+            # set an environment value, ensure that it's returned
+            os.environ["GLOBUS_SDK_ENVIRONMENT"] = "beta"
+            self.assertEqual(globus_sdk.config.get_globus_environ(), "beta")
+
+            # clear that value, "default" should be returned
             del os.environ["GLOBUS_SDK_ENVIRONMENT"]
-        self.assertEqual(globus_sdk.config.get_default_environ(), "default")
-        # otherwise environ value
-        os.environ["GLOBUS_SDK_ENVIRONMENT"] = "beta"
-        self.assertEqual(globus_sdk.config.get_default_environ(), "beta")
-
-        # cleanup for other tests
-        if prev_setting:
-            os.environ["GLOBUS_SDK_ENVIRONMENT"] = prev_setting
-        else:
+            self.assertEqual(globus_sdk.config.get_globus_environ(), "default")
+
+            # ensure that passing a value returns that value
+            self.assertEqual(
+                globus_sdk.config.get_globus_environ("beta"), "beta")
+
+    def test_get_globus_environ_production(self):
+        """
+        Confirms that get_globus_environ translates "production" to "default",
+        including when special values are passed
+        """
+        # mock environ to ensure it gets reset
+        with mock.patch.dict(os.environ):
+            os.environ["GLOBUS_SDK_ENVIRONMENT"] = "production"
+            self.assertEqual(globus_sdk.config.get_globus_environ(), "default")
+
             del os.environ["GLOBUS_SDK_ENVIRONMENT"]
+            # ensure that passing a value returns that value
+            self.assertEqual(
+                globus_sdk.config.get_globus_environ("production"), "default")
diff --git a/tests/unit/test_renewing_authorizer.py b/tests/unit/test_renewing_authorizer.py
index ed227b92..ffda8551 100644
--- a/tests/unit/test_renewing_authorizer.py
+++ b/tests/unit/test_renewing_authorizer.py
@@ -105,7 +105,7 @@ class RenewingAuthorizerTests(CapturedIOTestCase):
         """
         Confirms nothing is done before the access_token expires,
         """
-        self.authorizer._check_expiration_time()
+        self.authorizer.check_expiration_time()
         self.assertEqual(self.authorizer.access_token, self.access_token)
 
     def test_check_expiration_time_expired(self):
@@ -113,7 +113,7 @@ class RenewingAuthorizerTests(CapturedIOTestCase):
         Confirms a new access_token is gotten after waiting for expiration
         """
         time.sleep(1)
-        self.authorizer._check_expiration_time()
+        self.authorizer.check_expiration_time()
         self.assertEqual(self.authorizer.access_token,
                          self.token_data["access_token"])
         self.assertEqual(self.authorizer.expires_at,
@@ -125,7 +125,7 @@ class RenewingAuthorizerTests(CapturedIOTestCase):
         Confirms a new access_token is gotten if the old one is set to None
         """
         self.authorizer.access_token = None
-        self.authorizer._check_expiration_time()
+        self.authorizer.check_expiration_time()
         self.assertEqual(self.authorizer.access_token,
                          self.token_data["access_token"])
         self.assertEqual(self.authorizer.expires_at,
@@ -137,7 +137,7 @@ class RenewingAuthorizerTests(CapturedIOTestCase):
         Confirms a new access_token is gotten if expires_at is set to None
         """
         self.authorizer.expires_at = None
-        self.authorizer._check_expiration_time()
+        self.authorizer.check_expiration_time()
         self.assertEqual(self.authorizer.access_token,
                          self.token_data["access_token"])
         self.assertEqual(self.authorizer.expires_at,

Creating a client with `environment="production"` does not properly translate as it would with the environment variable
The default config section has the "production" environment values.
We have handling code for this in `globus_sdk.config_get_default_environ`, but that only runs if `environment` isn't passed to a client.
As a result, config lookups are done against the `production` section and fail.

There are several ways of handling this, but one option which is probably pretty foolproof is to update this:
https://github.com/globus/globus-sdk-python/blob/d761ba9a104ba2d8a70d2e064d12ea95101596df/globus_sdk/base.py#L85-L86

Instead of doing that, try
```python
environment = config.get_default_environ(environment)
```
and update `get_default_environ` to take an input.
tests/unit/test_config.py::ConfigParserTests::test_get_globus_environ tests/unit/test_config.py::ConfigParserTests::test_get_globus_environ_production tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_check_expiration_time_expired tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_check_expiration_time_no_expiration tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_check_expiration_time_no_token tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_check_expiration_time_valid
tests/unit/test_config.py::ConfigParserTests::test_bool_cast tests/unit/test_config.py::ConfigParserTests::test_get tests/unit/test_config.py::ConfigParserTests::test_get_lib_config_path tests/unit/test_config.py::ConfigParserTests::test_get_parser tests/unit/test_config.py::ConfigParserTests::test_get_service_url tests/unit/test_config.py::ConfigParserTests::test_get_ssl_verify tests/unit/test_config.py::ConfigParserTests::test_init_and_load_config tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_get_new_access_token tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_handle_missing_authorization tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_init tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_authorization_header tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_authorization_header_existing tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_authorization_header_expired tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_authorization_header_no_expires tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_authorization_header_no_token tests/unit/test_renewing_authorizer.py::RenewingAuthorizerTests::test_set_expiration_time