This study examined the integrative complexity of thinking in individuals making the transition to parenthood, and the relationship between complexity and adjustment during this period. Sixty-nine couples were interviewed 3 months before their babies were born, and 6 months after the birth. The prenatal interview focussed on individuals' expectations about what it would be like being a parent; the postnatal interview focussed on individuals' actual experiences as parents. In addition, participants completed measures of depression, self-esteem, and marital satisfaction after each interview, and a measure of stress after the 6-month postnatal interview. Both men and women demonstrated a significant increase in the complexity of their thinking from the prenatal to the postnatal interview, with women demonstrating higher levels of complexity at both times. In addition, women with more complex expectations demonstrated better adjustment after their babies were born than did women with simpler expectations; these results were not obtained for men. Results are discussed with regard to the way in which thinking about the self changes as one negotiates major life transitions, and the way in which complex thinking can help counter some of the stresses that individuals may experience at these times.