Background: Colorectal cancer (CRC) survivors can improve their quality-of-life (QOL), and potentially survival, by engaging in physical activity. The aim of this pilot randomized controlled trial (RCT) is to determine the feasibility of a technology-based physical activity intervention for CRC survivors. Methods: 40 CRC survivors will be randomized (1:1) to a 12-week physical activity intervention (Fitbit Flex, daily text messages) or usual care. Eligible individuals must: 1) have stage I-III colon or rectal adenocarcinoma; 2) have completed therapy; 3) be considered cancer-free; 4) be English speaking; 5) have no contraindications to moderate physical activity; 6) engage in < 150 min/week of moderate physical activity; and 7) have Internet and a phone that can receive text messages. Our primary outcomes are adherence (e.g., Fitbit wear time, text response rate) and acceptability assessed via survey. Secondary outcomes include change in physical activity via 7-days of ActiGraph GT3X+ accelerometers and QOL. Results: We have screened 350 individuals with stage I-III CRC at the University of California, San Francisco (UCSF) for eligibility. Of these, 181 (52%) were not eligible [non-English speaking (46%), ≥ 150 min/week of physical activity (22%), contraindications to physical activity (22%), not cancer-free (7%), did not own a mobile phone (2%)]. We invited the remaining 169 eligible CRC survivors to participate by mail, e-mail, phone, or in clinic; 76 (45%) actively declined and 59 (35%) did not respond after up to 3 contact efforts. As of October 2016, 34 CRC survivors have been randomized to intervention (n = 16) or control (n = 18). These individuals are: 55% female; 64% Non-Hispanic White; 73% have a 4-y college degree; and 64% work full-time. The median (IQR) age and BMI are: 56 (50, 65) y and 26.4 (23.2, 32.4) kg/m², respectively. Conclusions: The results of this pilot study will inform a definitive RCT to determine whether a technology-based physical activity intervention improves QOL and survival after CRC diagnosis. Funding: This research was supported by the NIH (K07CA197077, KL2TR000143), Mt. Zion Health Fund and UCSF Helen Diller Family Comprehensive Cancer Center.