This study examines variation in saving behavior of poor families enrolled in a children savings accounts program for orphaned and vulnerable school-going children in Uganda. We employ multilevel analyses using longitudinal data from a cluster-randomized experimental design. Our analyses locate the following significant results: (1) financial institutions' characteristics affect average monthly savings and deposit frequency; (2) reported high levels of family cohesion are associated with higher deposit frequency; (3) children in the care of female guardians report higher average monthly saving and deposit frequency. The study has the following key implications: institutions and family relations matter in children savings mobilization.