Objective: To assess the impact of a community based, low-contact intervention on the physical activity habits of insufficiently active women. Design: Randomized controlled trial. Participants: Inactive Irish women. Method: A population sample of women participating in a mass 10 km event were up followed at 2 and 6 months, and those who had relapsed to insufficient levels of physical activity were recruited to this trial and randomly allocated to an intervention or control group. A tailored physical activity booklet was mailed to participants in the intervention group; a placebo booklet was administered to the control group. Three weeks after the dissemination of materials, members of the intervention group were contacted by phone to check the receipt and use of the booklets. Six weeks post baseline, questionnaires were administered to all participants. Results: Receipt and use of materials and an increase in self-efficacy was significantly greater in the intervention group. Mean total physical activity increased significantly between baseline and follow-up in both the intervention (+ 109 min) and control groups (+ 139 min), with increases most apparent among the least active participants of both groups. There was also a significant increase in the number of respondents meeting minimum physical activity guidelines at follow-up. Conclusion: There was no difference in the increases in physical activity, which were greatest among least active participants, between intervention and control groups, suggesting that the tailored materials used in this trial did not have a greater impact than standard health information and contact alone. (Contains 3 tables.)