Resilient, undercontrolled, and overcontrolled personality types have been identified across the life span and are associated with psychiatric symptoms and functioning. However, it is unknown whether these types are identifiable in preschool-aged children using observational indices or whether they predict longitudinal outcomes. The current study used observationally coded five-factor model (FFM) traits in a sample of preschoolers to identify whether personality traits cluster into types, whether types predict psychiatric symptoms and impairment across development, and whether types better predict outcomes than trait dimensions. Using a validated "thin slice" approach, preschool personality was observationally coded in a clinically enriched sample oversampled for depression (N = 299). Latent class analysis tested how FFM dimensions organized into types, identifying resilient, undercontrolled, and overcontrolled preschoolers. Types demonstrated baseline diagnostic differences and multilevel models indicated above baseline diagnoses, undercontrolled children exhibited elevated externalizing symptoms and worse functioning across development, whereas overcontrolled and resilient children did not differ. Personality types and dimensions both provided similar predictive utility. Resilient, undercontrolled, and overcontrolled personality types are identifiable using FFM observational coding in clinically heterogeneous preschoolers and undercontrolled children demonstrated the most severe trajectories. Findings highlight that personality types are detectable at early ages and have unique predictive power for psychiatric outcomes across development compared with dimensions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).