["Journal of Personality, EarlyView. ", "\nABSTRACT\n\nObjective\nUnderstanding when and why people become lonely is of theoretical and practical relevance. Personality traits and loneliness have been theorized to reciprocally influence each other over time. However, longitudinal research on personality‐loneliness transactions remains scarce, and existing studies yielded inconsistent findings.\n\n\nMethods\nTo advance understanding of the longitudinal transactions between loneliness and the Big Five personality traits, this study analyzed data from three large‐scale panel studies (N = 63,502) using random‐intercept cross‐lagged panel models.\n\n\nResults\nMeta‐analytic aggregation of findings across datasets indicated that, relative to individuals' typical levels, higher levels of extraversion (β = −0.04), conscientiousness (β = −0.02), and emotional stability (β = −0.04) at a given time point prospectively predicted lower levels of loneliness 4 years later. In turn, higher levels of loneliness prospectively predicted lower levels of extraversion (β = −0.03), conscientiousness (β = −0.02), and emotional stability (β = −0.02) 4 years later. Notably, while the meta‐analytic cross‐lagged effects were generally small, effect sizes varied substantially across the individual datasets.\n\n\nConclusion\nOverall, the present findings point to a dynamic, reciprocal relationship between loneliness and the Big Five traits, suggesting that these traits both influence and respond to loneliness.\n\n"]