Previous theory and research linked perfectionism to contingent self-worth and conditional acceptance, but little research directly investigated how adolescents’ perfectionism and their perceived family acceptance shape each other over time. The present study is the first to investigate the reciprocal longitudinal relations between adolescents’ perfectionism and their perceived family acceptance. The study examined a sample of 264 adolescents (aged 14–19 years) over a period of 3 months, using a cross-lagged longitudinal design with two time points. Results showed that perfectionistic standards predict relative increases, whereas perfectionistic concerns predict relative decreases in adolescents’ perceived mother, father, and family acceptance. However, perceived family acceptance did not predict significant changes in perfectionistic standards nor in perfectionistic concerns. Considering this, the results emphasize the role of perfectionism as a predictor for perceptions of mother, father, and family acceptance and capture how perfectionism may shape interpersonal experiences within the family. Implications of these findings for both research and practice are discussed.