The study was based on the assumption that stressors in the lives of pregnant and parenting women are processes that affect prenatal, postpartum, and concurrent maternal hormones and emotions and that these processes affect child temperament. The hypotheses were tested in a group of 67 young mothers and their 3-year-old children. Mothers were clustered into groups based on longitudinal patterns of hormones and emotions at prenatal, postpartum, and 3-year follow-up assessments. The analyses focused on relating maternal patterns of hormones and emotions to the child's temperament at age 3 years. Temperament was assessed by questionnaire and observation of behavior during a challenging situation. Illustrative findings included the following. Verbal aggression and nonverbal aggression were significantly higher in children of mothers in the low prenatal hormone cluster than children of mothers in the high prenatal hormone cluster. Children of mothers in the postpartum low testosterone (T), estradiol (E2), and androstenedione (Δ4-A) and medium cortisol (Cort) cluster (mainly low hormone cluster) exhibited significantly more physical aggression than children of mothers in the medium T and Δ4-A, high E2 and low Cort cluster. Maternal patterns of hormones, emotions, and parenting attitudes and practices were related to multiple aspects of temperament when the children were age 3 years. The findings support the important role of maternal biological and psychological processes in the development of child temperament.