This study sought to verify the stages of concern theory according to Hall, Wallace, and Dossette (1973), using a school-wide educational reform. Furthermore, changes in teachers' concern profiles as a function of education levels, teaching areas, hours of reform-related training, and adoption-proneness were studied. In particular, teachers' concern profiles about implementing the High Schools That Work (HSTW) reform in Virginia were studied. One thousand two hundred and seven teachers in 19 sites implementing the HSTW reform in Virginia participated in the study. Of the purposive sample of 1207 teachers to whom study questionnaires were forwarded by mail, 674 responded and returned their questionnaires. The questionnaire consisted of three sections: the Stages of Concern section (Hall, Wallace, & Dossette, 1973), the Adoption-proneness section (Oscarson, 1977), and the demographic information section. Data were analyzed, using descriptive statistics and multivariate analysis of variance procedures (α = .05). Results revealed that teachers with no HSTW reform experience (N = 131) had highest concern at the personal stage, followed by teachers in their first year of experience (N = 207), and teachers in their second year of experience (N = 230). Teachers in their third year of experience (N = 70) revealed the least concern at the personal stage. There was significant change in teachers’ concern associated with amount of experience F(21, 1880) = 12.32, p = .00 (p < .05). Teachers with more experience had peak concerns at the consequences and collaboration stages while teachers with less experience had peak concern at the personal stage. Results agreed with the theory which states that as experience in reform use increases, concern moves from informational and personal stages to consequences and collaboration stages. Change in teachers’ concern as a function of education level was significant F(28, 2502) = 2.09, p = .001 (p < .05). Teachers with doctoral degrees, followed by those with 30 credit hours above the master's degree, revealed more collaboration concern than teachers with associate, bachelor’s, and master's degrees. Concern change due to teaching area was not significant F(7, 630) = 1.81, p = .08 (p > .05). The concern profiles of vocational and academic teachers were parallel and coincident, but not level. Teachers’ concern change as a function of hours of related training was significant F(14, 1256) = 12.12, p = .00 (p< .05). Teachers with no reform-related training had peak concern at the personal stage while those with more than 15 hours of training had peak concerns at the collaboration and consequences stages. Teachers who had 15 hours or less of training had lower personal concern than those who had no training, but higher than those who had more than 15 hours of training. Teachers’ concern as a function of adoption-proneness was significant F(7, 630) = 14.53, p = .00 (p < .05). While all the teachers revealed similar informational, personal, and management concerns, teachers who were more adoption-prone had more intense concern at the consequences and collaboration stages. / Ph. D.