diff --git a/vistautils/newsfragments/71.feature b/vistautils/newsfragments/71.feature
new file mode 100644
index 0000000..7966e7f
--- /dev/null
+++ b/vistautils/newsfragments/71.feature
@@ -0,0 +1,1 @@
+Environmental variables are now interpolated into parameters loaded from YAML by default
diff --git a/vistautils/parameters.py b/vistautils/parameters.py
index 8f8724d..c840339 100644
--- a/vistautils/parameters.py
+++ b/vistautils/parameters.py
@@ -712,14 +712,14 @@ class YAMLParametersLoader:
     string (and the `%`s) with the value of the parameter.  Failed interpolations will result
     in a `ParameterError`.
 
-    If *interpolate_environmental_variables* (default: false) is specified, then environmental
+    If *interpolate_environmental_variables* (default: true) is specified, then environmental
     variables will be available for interpolation, though they will not themselves appear in the
     loaded parameters.  Explicitly-specified parameters have priority over environmental variables.
 
     See unit tests in `test_parameters` for examples.
     """
 
-    interpolate_environmental_variables: bool = False
+    interpolate_environmental_variables: bool = True
 
     def load(
         self,

diff --git a/tests/test_parameters.py b/tests/test_parameters.py
index 0e38f3b..1e0f346 100644
--- a/tests/test_parameters.py
+++ b/tests/test_parameters.py
@@ -235,7 +235,7 @@ class TestParameters(TestCase):
             )
 
     def test_environmental_variable_interpolation(self):
-        loader = YAMLParametersLoader(interpolate_environmental_variables=True)
+        loader = YAMLParametersLoader()
         os.environ["___TEST_PARAMETERS___"] = "foo"
         os.environ["___TEST_CLASHING_PARAM___"] = "bar"
         loaded_params = loader.load_string(ENV_VAR_INTERPOLATION_INPUT)

Make parameters interpolate environmental variables by default
We want this behavior more frequently than we don't.  Since explicitly-defined variables trump environmental variables anyway, this is unlikely to cause surprising behavior.
tests/test_parameters.py::TestParameters::test_environmental_variable_interpolation
tests/test_parameters.py::TestParameters::test_boolean tests/test_parameters.py::TestParameters::test_double_context_fail tests/test_parameters.py::TestParameters::test_float tests/test_parameters.py::TestParameters::test_inclusion tests/test_parameters.py::TestParameters::test_interpolation tests/test_parameters.py::TestParameters::test_optional_existing_directory tests/test_parameters.py::TestParameters::test_optional_existing_file tests/test_parameters.py::TestParameters::test_string tests/test_parameters.py::TestParameters::test_writing_to_yaml