Background: Adolescent girls are at an increased risk of low physical activity and the associated health consequences. Girls Can Move!, an after-school intervention guided by social cognitive theory, was designed to increase physical activity. Purpose: To examine the feasibility and initial effectiveness of Girls Can Move! Methods The 8-week pre-post intervention provided low-active adolescent female participants with a variety of physical activities led by active female role models. Attendance, weekly process evaluations, and a post-intervention focus group were used to assess satisfaction and feasibility. At pre- and post-intervention, participants wore an accelerometer for 7 days to measure physical activity. Results: Of the 17 enrolled participants, 13 (11.7 ± 0.7 years, 82% Black/African American or multiracial) completed the intervention. The average attendance rate was 82%. On a scale from 1 to 5, participants reported the sessions were fun (4.5 ± 0.6) and increased their confidence (4.1± 0.5) and physical activity (4.1± 0.5). There were moderate-to-large increases in objectively measured physical activity (d = 0.71). Discussion: Girls Can Move! is feasible and should be tested using a randomized controlled trial design. Translation to Health Education Practice: Girls Can Move! can be implemented in after-school settings with the support of university and community partners to promote physical activity among adolescent girls.