This study assessed whether the Center for Epidemiological Studies Depression Scale (CES-D) functions equivalently in assessing depressive symptom severity in lesbian, bisexual, and heterosexual women. Using differential item functioning methods, the authors examined (a) whether there is a bias in CES-D total scores and in individual item scores and (b) whether there are differences across female sexuality groups in the construct of depression assessed by the CES-D. Data were collected anonymously online from 273 women. The CES-D total score was unbiased across groups, but there were biases and construct differences in some individual symptoms. Thus, the findings suggest not only that researchers and clinicians can feel secure in using the CES-D in women of different sexual orientations but also that there may be interesting group differences in the manifestation of particular depressive symptoms. (Contains 1 table and 1 note.)