Background: In 2011, the YMCA of the United States adopted physical activity standards for all their afterschool programs (ASPs), which call for children to accumulate 30 minutes of moderate-to-vigorous physical activity (MVPA) while attending YMCA ASPs. The extent to which youth attending YMCA ASPs achieve this standard is unknown.Methods: Using a cluster-stratified design, 20 ASPs were sampled from all YMCA-operated ASPs across South Carolina (N = 102). ASPs were visited on four unannounced, nonconsecutive weekdays. Accelerometer-derived minutes spent in MVPA were dichotomized to ‡30 min/d of MVPA and <30 min/d of MVPA. Program characteristics were measured through document review and direct observation and compared to MVPA levels using random-effects quantile regression.Results: Boys (n = 607) and girls (n = 475) accumulated a median of 25.3 and 17.1 min/d of MVPA, respectively, which translated into 33% (range 6.2%-67.3%) and 17% (0%-42.6%) achieving the 30 min/d of MVPA standard, respectively. Increase in time scheduled for activity (10.7-11.7 min/d of MVPA), limited sedentary choices during activity time (6.9-8.9 min/d of MVPA), and staff activity-promotion training (4.8-7.9 min/d of MVPA) were associated with higher accumulated minutes of MVPA for boys and girls. Program revenue, percent activity structure that was for free play, and indoor/outdoor space were inconsistently related to meeting the MVPA standard.Conclusions: Modifiable programmatic structures were associated with higher amounts of MVPA. These findings suggest that simple programmatic changes could help ASPs to achieve the MVPA standard, regardless of infrastructure or finances.