Phillips began teaching during the Great Depression. Initially, she took part-time and temporary positions at Battle Creek College (1928–30) and at Connecticut College for Women (1937–38). Phillips also held postdoctoral fellowships at the University of California and at Bryn Mawr College. In early 1936 the American Association of University Women announced that Philips was the recipient of its Margaret E. Maltby award, one of six women to receive its research fellowships for the 1936–37 academic year. Phillips's research focused on application of quantum mechanics to the study of nuclear physics. Before accepting a full-time faculty position at Brooklyn College in 1938, Phillips worked as a fellow at the Institute for Advanced Study in Princeton, New Jersey.