BackgroundDepression is a global health burden, disproportionately affecting women. A lack of contextual, real-life assessments considering the oft-gendered context (e.g., expression) of daily symptom fluctuations may contribute to this disparity. The current study examines: a) gender differences in daily depressive symptoms – and fluctuations; and b) daily links between self-perceived gender expression and depressive symptoms. MethodsEstablished adults (N=96; Mage=28.19, SDage=8.43) participated in an ecologically-valid multi-wave 100-day intensive longitudinal study. They reported daily on their depressive symptoms and on their self-expression (in the final study wave). Gender differences in daily symptoms fluctuations (intraindividual standard deviations) and their links to gender expression (person-specific residualized correlations) were examined. ResultsWomen experienced greater day-to-day symptom fluctuations than men, after accounting for the gender difference in baseline symptoms (b=-.05; 95% CI: [-.093, -.012]). Results from a subsample (n=28) showed that daily links between gender expression and depressive symptoms were heterogeneous: For 38.5% of men and 53.3% of women, daily increases in congruent gender expressions (i.e., masculine for men and feminine for women) corresponded with daily symptom decreases, but a notable proportion (46.4%) did not show meaningful relations. ConclusionsResults highlight the utility of intensive longitudinal approaches for the study of depression and, for some people, the daily psychological consequence of gender self-perceptions. Results also emphasize heterogeneity in depression etiology and the need for personalized basic and applied science. LimitationsFuture research on individuals with varying gender identities and clinical experiences is needed.