e24144 Background: Depressive symptoms are common among women undergoing chemotherapy (CTX) for breast or gynecological cancer. Many studies have examined the prevalence of depressive symptoms (usually at the beginning or end of CTX). However, given that CTX unfolds over a number of cycles, there is a need to better understand patterns of change in depressive symptoms over the course of treatment, and to identify factors that may predispose individuals to worse symptom trajectories. The purpose of this study, among women who underwent CTX for breast or gynecological cancer, was to evaluate for interindividual differences in depressive symptoms over the course of two cycles of CTX, and to identify characteristics associated with both initial levels (i.e., at the beginning of the study) and trajectories of depressive symptoms. Methods: Patients undergoing CTX for breast (n = 530) or gynecologic (n = 233) cancer completed the Center for Epidemiological Studies-Depression (CES-D) questionnaire six times over two treatment cycles. Patient-reported measures were used to assess demographic, clinical, symptom, stress, and coping characteristics at enrollment. Using hierarchical linear modeling (HLM), we evaluated characteristics associated with initial levels and trajectories of depressive symptoms. Results: One demographic (marital status) and two clinical (number of comorbidities, functional status) characteristics predicted interindividual differences in initial levels of depressive symptoms. One demographic (education) and one clinical (MAX-2 score, a CTX toxicity metric) characteristic were associated with interindividual differences in depressive symptom trajectories. Several symptom characteristics predicted interindividual differences in initial levels (i.e., morning fatigue), trajectories (i.e., initial level of depression), or both initial levels and trajectories (i.e., sleep disturbance, attentional function) of depressive symptoms. Two stress-related variables (i.e., perceived stress, cancer-related distress) predicted interindividual differences in both initial levels and trajectories of depressive symptoms. Several coping variables predicted interindividual differences in initial levels (i.e., behavioral disengagement), trajectories (i.e., venting), or both initial levels and trajectories (i.e., self-blame) of depressive symptoms. Conclusions: The range of demographic, clinical, symptom, stress and coping characteristics associated with interindividual differences in depressive symptoms underscores the importance of evaluating risk and protective factors. These factors may serve as useful markers for both screening and intervention to address depressive symptoms during CTX.