Although individuals vary in how optimistic they are about the future, one assumption that researchers make is that optimism is sensitive to changes in life events and circumstances. We examined how optimism and pessimism changed across the lifespan and in response to life events in three large panel studies (combined N = 74,886). In the American and Dutch samples, we found that optimism increased across younger adulthood, plateaued in midlife, and then decreased in older adulthood. In the German sample, there were inconsistent results with respect to age differences and mean level changes in optimism. Associations between life events and changes in optimism/pessimism were inconsistent across samples. We discuss our results in the context of life events and lifespan development.