Research on the effect of email-delivered, pedometer-based interventions on walking behavior and transtheoretical model (TTM) constructs is lacking. Therefore, the purpose of this study was to compare the effectiveness of two email-delivered, pedometer-based interventions designed to increase walking and TTM construct scores among insufficiently active women. Participants were randomly assigned to one of two 6-week intervention groups. Both groups wore pedometers, submitted step logs, and received weekly email reminders. One group also received in the emails suggested strategies based on TTM for increasing physical activity. Of the 74 women who began the study, 56 (age=41.5+/-7.6 years; body mass index=31.2+/-6.6kg/m(2); 86% Caucasian) completed the International Physical Activity Questionnaire and TTM questionnaires at baseline and post-intervention. Participants in both groups combined increased weekly time spent walking (p=0.002) and their scores on TTM cognitive processes, behavioral processes, pros, and cons changed (p< or =0.001) from baseline to post-intervention. The changes in walking and TTM scores did not differ between groups (p>0.05). The results of this study indicate that email-delivered, pedometer-based interventions may impact walking and most TTM scores among insufficiently active women. Although preliminary, the findings provide additional evidence that this low-cost method of intervening may be an effective approach to combat physical inactivity in women.