["Journal of Personality, EarlyView. ", "\nABSTRACT\n\nObjective\nWhile loneliness is intertwined with many mental and physical health problems, its origins are not yet well understood. We sought to better understand its link to personality in a large national cohort.\n\n\nMethods\nCombining self‐ and informant ratings in multiple samples, we conducted the largest study to date to examine loneliness' true correlations (rtrues) with the Big Five personality traits, free of single‐method biases and transient and random errors.\n\n\nResults\nAcross three samples (Estonian‐speaking, N = 20,893; Russian‐speaking, N = 762; English‐speaking, N = 599), we found a strong relationship between loneliness and Neuroticism (rtrue = 0.60–0.70). Loneliness also had robust but much weaker associations with Extraversion (rtrue = −0.20 to −0.30), and only weak associations (rtrue = 0.10 to −0.20) with Agreeableness, Conscientiousness, and Openness. Collectively, the Big Five accounted for over 50% of loneliness variance. In a subsample, the associations were only slightly smaller longitudinally over approximately 10 years.\n\n\nConclusion\nOverall, feeling lonely is more closely related to Neuroticism than previously understood, and the association endures over time.\n\n"]