This study investigated the type and stability of temperament profiles in toddlers, and relations of profile probability to negative and positive parenting trajectories. Mothers (N = 96) rated their child's (41 girls and 54 boys) Sociability, Anger Proneness, and Activity Level four times during 1 year. The assessment of parenting included both maternal self-reports and observational measures. Latent profile analysis indicated three child temperament profiles: a well-adjusted "typical" profile, an "expressive" profile with heightened externalizing problems, and a "fearful" profile with heightened internalizing problems. Although toddlers' profile classifications were highly stable across 1 year, individual differences in (changes in) toddlers' temperament profile probability occurred. We identified negative and positive parenting as environmental mechanisms that were related to the development of temperament profiles over time. These results support the notion that, in addition to having a genetic base, temperament is subject to maturation and experience over time. (Contains 1 table and 2 figures.)