BACKGROUND: African American women report low levels of physical activity (PA) and are disproportionately burdened by related chronic diseases. This pilot study tested a 6-month theory-based (Social Cognitive Theory, SCT) culturally-relevant website intervention to promote PA among African American female college students. MATERIALS AND METHODS: A single group pre-post test design (n=34) was used. PA and associated SCT constructs (outcome expectations, enjoyment, self-regulation, social support) were assessed at baseline, 3 months and 6 months. RESULTS: The sample was comprised of mostly obese (M BMI= 35.4, SD=6.82) young adults (M age= 21.21 years, SD=2.31). Fifty percent of the sample completed all assessments. Intent-to-treat analyses showed that participants reported a significant median improvement in moderate-to-vigorous physical activity from 82.5 minutes/week (M=81.76, SD=76.23) at baseline to 115.0 minutes/week (M=122.44, SD=97.93) at 3 months (Wilcoxon z=2.39, p=.02). However these gains appear to have attenuated by 6 months (Median= 82.5 minutes/week, M=96.73, SD=84.20; Wilcoxon z=1.02, p=.31). Significant increases from baseline to 6 months were found in self-regulation for PA (p=.02) and social support for PA from friends (p=.02). Changes in the SCT variables were not significantly associated with changes in PA; however, this may have been due to small sample size. CONCLUSIONS: Future studies with larger samples and more aggressive retention strategies (e.g., more frequent incentives, prompts for website use) are needed to further explore the applicability of web-based approaches to promote PA in this at-risk population.