OBJECTIVE Brief interpersonal psychotherapy (IPT-B) has been shown to be effective in treating perinatal depression and in preventing depressive relapse among socioeconomically disadvantaged women. Yet, it is unclear how IPT-B alleviates depression. Previous research has suggested four possible change mechanisms derived from IPT's interpersonal model: decreasing interpersonal stress, facilitating emotional processing, improving interpersonal skills, and enhancing social support. This study explored how women who received IPT-B or enhanced maternity support services (MSS-Plus) evaluated their respective experiences. METHODS A qualitative study was conducted with 16 women who had been recruited from public health clinics to participate in a larger, randomized controlled trial of women with major depression or dysthymia and who had been assigned to receive IPT-B or MSS-Plus. The sample was 63% non-Hispanic White, had an average age of 31.6 years, and was balanced in intervention group assignment, posttraumatic stress disorder status, and depression improvement. Telephone interviews included semistructured, open-ended questions eliciting participants' experiences with depression treatment. Predetermined, conceptually derived codes were based on the four postulated IPT change mechanisms. RESULTS Thematic coded excerpts were collected and discussed. Excerpts lent support to the role of IPT-B in helping women decrease their interpersonal stress; identify, reflect on, and regulate their emotions; and improve their social skills. Evidence for increasing social support was mixed but highlighted the importance of the therapeutic relationship. CONCLUSIONS Including qualitative findings into training in public health and other clinical settings will help illuminate the role of the provider in facilitating the change mechanisms that may lead to improved mental health among clients.