The Affective Neuroscience Personality Scales (ANPS) is a personality instrument based on six evolutionary-related brain systems that are at the foundation of human emotions and behaviors: SEEKING, CARING, PLAYFULNESS, FEAR, ANGER, and SADNESS. We sought to assess for the short and long versions of the ANPS: (a) the longitudinal measurement invariance and long-term (4-year) stability and (b) the sex measurement invariance. Using data from a Canadian cohort (N = 518), we used single-group confirmatory factor analysis to assess longitudinal invariance and multiple-group confirmatory factor analysis to assess sex invariance, according to a five-step approach evaluating five invariance levels (configural, metric, scalar, residual, and complete). Results supported full longitudinal invariance for both versions for all invariance levels. Partial residual invariance was supported for sex invariance. The long-term stability of both versions was good to excellent. Implications for personality assessment and ANPS development are discussed.