▼ Although the benefits of physical activity are well known, most adults in the U.S.A. are relatively sedentary, with about 60% of adults not regularly physically active and 25% of those are not active at all. This level of inactivity places the population at risk, medically and financially, for many chronic diseases (CDC, 1999). The purpose of this study was to test the effectiveness of tailored e-mail communications designed to increase intentional physical activity in a group of employees. The specific aims were: 1) to examine the messages' effect on stage movement progression for participants in either Contemplation or Preparation stage-of-change; and 2) to examine the messages' effect on increasing the workers' physical activity levels. A synthesized theoretical model based on TTM and Maslow's Hierarchy of Needs (Yap & Davis, 2007) guided message development and provided a framework for understanding the process of increasing intentional physical activity. A quasi-experimental design (two groups, repeated measures) was used. Two manufacturing plants from a multinational company, served as study sites (n = 36 from intervention plant; n = 37 from control plant). The intervention group received tailored messages weekly for six weeks, and the control group recieved sham health messages. The dependent variables were: 1) movement to a higher level of the stages-of-change, measured by a staging questionnaire and 2) an increase intentional physical activity in the intervention group, measured by an accelerometer. Ordinal regression revealed a small effect size for participants in the combined Contemplation and Preparation stages, but a medium effect size for the Contemplation participants. A two-way repeated ANOVA for steps by groups showed a steps main effect Λ = .89, F (3, 63) = 2.37, p = .039, and groups by steps interaction, Λ = .87, F (3, 63) = 2.95, p = .019. The positive direction of the process of behavioral change, combined with the increase in overall physical movement shows promise for future workplace interventions. Theory will now be directed toward strengthening the needs level concept and refining the messages. Research will be directed toward increasing power and the length of the intervention. Advisors/Committee Members: Davis, L. Sue.