This study retrospectively examined physical activity patterns across three specific age periods (childhood, teenage, and young adulthood) in a cross sectional sample of young Caucasian undergraduate women (N = 44). All women (mean age = 22.27 plus or minus 3.14 years) completed questionnaire packets assessing transtheoretical model of behavior change constructs. Additionally, each woman completed a detailed historical physical activity oral interview with the investigator. Physical activity decreased significantly across all age groups. Physical activity during ages 13 to 18 and 19 years and older, counterconditioning (i.e., substituting physical activity for other behaviors), self-liberation (i.e., making a commitment to adopt an active lifestyle), self-reevaluation (i.e., recognizing the personal importance of physical activity in one's life), reinforcement management (i.e., rewards associated with physical activity), physical activity during ages 6 to 12 years, and dramatic relief (i.e., experiencing negative emotions associated with physical inactivity) had the strongest relationship with current physical activity participation. Cons (i.e., costs associated with physical activity participation) were negatively correlated with current physical activity patterns. Results suggest a need to identify additional correlates and mediators of physical activity participation in this population. (Contains 3 tables and 1 figure.)