ObjectivesTo examine whether (a) as people age, accumulation of negative events increases (“sensitizing”) or decreases (“steeling”) the detrimental effects of subsequent events on depressive symptoms, and (b) how particular psychosocial factors are associated with the strength of these steeling or sensitizing effects.MethodWe used data from 6 measurement waves from 2,069 adults aged 55–84 (M = 68.0) at baseline in the Longitudinal Aging Study Amsterdam, the Netherlands. We included 18 different life events across the life course. Using hybrid multilevel models, we tested whether the effects of proximate life events (<3 years) on depressive symptoms (measured by the Center for Epidemiologic Studies Depression scale) were moderated by previous cumulative events (childhood until previous measurement wave). Additionally, we tested whether education, mastery, emotional support, neuroticism, having strong faith, and loneliness were associated with the strength of steeling/sensitizing effects.ResultsCumulative and proximate life events were independently associated with more depressive symptoms. Interaction effects indicated that the more cumulative life events, the weaker the effects of recent life events, suggesting a “steeling” effect. Unexpectedly, 3-way interaction effects showed that higher mastery and lower neuroticism were associated with weaker steeling effects. These effects were predominantly attributable to within-person changes rather than to fixed between-person differences. Results from analyses with event severity scores were similar.ConclusionsAs a population, older adults appear to become more resilient against new stressors as they accumulate experience in dealing with negative life events. Findings on mastery tentatively suggest that accepting limits to one’s own control over life circumstances may foster a steeling effect.