Preservice teachers hold strong beliefs prior to entering their preparation programs (Lortie, 1975, Pajares, 1992). These beliefs act as screens through which to filter new information and influence how teachers interpret and assimilate teacher preparation program messages. (Matanin, & Collier, 2003). Pajaes (1992) argues that “beliefs are the best indicators of the decisions that individuals make throughout their lives” (p.307), and that preservice teachers may accommodate new information if a current belief is unsatisfactory, challenged and incongruent with an existing one. Although measurement of teacher beliefs is difficult, Graber (1998) suggests, “it is possible for an investigator to develop a fairly accurate picture of beliefs through means such as prolonged contact with participants, and comparison of verbal assertions with actual pedagogical behaviors” (p.141). In physical education, the Value Orientation Index has been useful in determining the influence of teachers’ educational values and beliefs (described as value orientations) on their goals and objectives for physical education. (Ennis, 1994; Ennis & Hooper, 1998). The purposes of this study were to examine the impact of a 15 month professional development program on the beliefs and values of 26 experienced urban physical education teachers, and to determine how their physical educational programs changed over time. During the intervention, data were collected using questionnaires (including pre and post VIO-2), both individual and small group interviews, and field notes gathered from nine workshops and a select number of the 152 total classes attended as professional development facilitators of the grant. Findings from the corpus of data show that both beliefs and practices of inservice teachers changed following the prolonged, guided intervention. The data revealed a reduction in the number of teachers who placed a high priority on the disciplinary mastery value orientation and moved toward a more student-centered approach to curriculum, allowing students greater choice from pre to post intervention. One of the teachers reflected: “The grant enabled me to change my curriculum and start to give choices to the students by giving them responsibility. Before I was unwilling to loosen control, but giving the students responsibility within classes has been such a positive experience for me”. Although preexisting beliefs may continue to filter information as teachers continue in their career (Graber, 1998), evidence from this study suggests these beliefs may be mediated by a prolonged systematic intervention which has implications for design and delivery of professional development. Keyword(s): professional development, professional preparation, research