Depression is a prevalent mental health condition that also often affects older adults. The PROACTIVE psychosocial intervention was developed to reduce depressive symptomatology among older adults within primary care settings in Brazil. An important psychological marker that affects individuals' aging experience relates to how old people feel. Known as subjective age, this marker has been shown to be a risk factor for experiencing greater depressive symptoms if individuals report feeling older than their (chronological) age. In this study, we perform secondary analyses of the PROACTIVE cluster-randomized controlled trial to examine the role of subjective age. The sample included 715 Brazilian older adults (74% female, 68.6, = 6.9, age range: 60-94 years) randomized to intervention ( = 360, 74% female, 68.4, = 6.6, age range: 60-89 years) or control ( = 355, 74% female, 68.9, = 7.2, age range: 60-94 years) arms. Here our primary outcome was depressive symptoms at the 8-month follow-up assessed with the 9-item Patient Health Questionnaire (PHQ-9) as a continuous variable. Our previous analyses demonstrated improved recovery from depression at follow-up in the intervention compared with the control arm. Relevant main effects and interactions in regression models for PHQ-9 presented here found that those reporting older subjective age had worse depressive symptoms at follow-up but that they benefitted more from the intervention when initial levels of depression were high. For participants who reported younger subjective ages the intervention showed positive effects that were independent of initial levels of depression. Our findings emphasize the importance of investigating possible underlying mechanisms that can help clarify the impact of mental health interventions.