The study found a significant increase in maternal harsh parenting (harsh verbal and physical abuse) involving children from birth to age 3, with the increase particularly pronounced when children were between ages 1 and 2. Regarding risk factors, there was a significant direct effect between maternal alcohol use and the mother's personal childhood abuse history on maternal harsh parenting at age 3, and maternal age was positively associated with change in maternal harsh parenting over time. In addition, partner aggression was significantly and positively associated with maternal harsh parenting at each time point examined. The overall high prevalence rates of harsh parenting and the growth of such behavior during infancy and toddlerhood indicates the need for developmentally sensitive early intervention programs. The longitudinal data were obtained from four assessments of a community sample of 488 at-risk mothers using latent growth curve modeling. Maternal risk factors and harsh parenting behavior were assessed at birth and at ages 1, 2, and 3. Maternal harsh parenting was measured with a modified version of the Parent-Child Conflict Tactics Scale. Other variables measured were maternal age at baseline, household income at baseline, maternal history of criminality and mental illness, maternal history of personal abuse in childhood, maternal depressive symptoms, maternal alcohol use, and partner aggression. 1 table, 1 figure, and 64 references