Relative to younger adults, older adults attend to and remember positive information more than negative information. This shift from a negativity bias in younger age to a preference for positive information in later life is termed the 'positivity effect.' Based on nearly two decades of research and recent evidence from neuroscience, we argue that the effect reflects age-related changes in motivation that direct behavior and cognitive processing rather than neural or cognitive decline. Understanding the positivity effect, including conditions that reduce and enhance it, can inform effective public health and educational messages directed at older people.