This study examines how study participants' financial knowledge and participation in a Child Development Account intervention affects 529 College Savings Plan account holding among caregivers of infants. The study uses data from the SEED for Oklahoma Kids (N = 2,651), a statewide randomized experiment using a probability sample of infants selected from birth records. Results of logit regression show that participants' financial knowledge is positively related to account holding in the treatment group but not in the control group. The interactive effects between financial knowledge and treatment status are statistically significant. This finding implies that the effect of financial knowledge on financial decisions related to college savings is moderated by institutional features, such as incentives, information and access. Results of this study support the propositions of financial capability and suggest that expanding financial capability requires both improved individual financial knowledge and supportive policy.