Background: Physical activity interventions designed for Latinas have shown short-term behavior change, but longer-term change and maintenance is rarely measured. Purpose: To assess physical activity change at 12 months, following 6-month tapered completion of an RCT of a physical activity intervention for Latinas. Methods: Two hundred sixty-six underactive (<60 minutes/week physical activity) Latinas were randomized to an individually tailored, culturally and linguistically adapted physical activity intervention, or a wellness contact control. Participants received the materials through the mail for 6 months, then received booster doses at 8, 10, and 12 months. Minutes per week of moderate to vigorous physical activity were measured by the 7-Day Physical Activity Recall interview at baseline and 6 and 12 months. Data were collected at Brown University between 2009 and 2013, and analyses were conducted in 2013. Results: At 12 months, increases in moderate to vigorous physical activity were significantly greater in the intervention than in the wellness group (mean difference=52 minutes/week, SE=9.38, p<0.01), with both groups showing slight increases in moderate to vigorous physical activity from 6 to 12 months. Intervention participants were also more likely to meet national moderate to vigorous physical activity guidelines (OR=3.14, p=0.01). Conclusions: The intervention was more effective than the wellness control at 12 months, and physical activity increases from baseline to 6 months were maintained, suggesting the intervention may lead to sustainable behavior change. Trial registration: This study is registered at Clinicaltrials.gov NCT01583140.