In the current study, latent growth modeling (LGM) was used to: (1) identify the developmental trajectories of infant negative emotions (NE) and regulatory capacity (RC) from 4 to 12 months of age, (2) examine maternal and family factors that may affect NE and RC trajectories, (3) examine transactional associations between developing NE and RC, and (4) examine the effect of infant temperament trajectories on negative parenting when toddlers reached 18 months of age. Mothers from 156 families completed a measure of infant temperament when infants were 4, 6, 8, 10, and 12 months of age and completed maternal relationship stress, depression, and family demographics measures when infants were 4 months of age. Information regarding negative parenting was collected when toddlers reached 18 months of age. LGM results suggest that maternal relationship stress and depression influence infant NE development, that high NE early in infancy may compromise the development of infant regulation, and that steeper decreases of infant RC contribute the greatest amount of variance to negative parenting in toddlerhood. The implications for models of early emotion regulation and incorporating changes in temperament over time into developmentally sensitive models (e.g., emerging parenting practices and developmental psychopathology) are discussed.