In 2010, the Wolf Trap Foundation for the Performing Arts, Institute for Early Learning Through the Arts (Wolf Trap), was awarded a U.S. Department of Education Arts in Education Model Development and Dissemination (AEMDD) grant. The purpose of the AEMDD grant was to develop, implement, and disseminate a research-based program of professional development that equips teachers to infuse mathematics instruction with performing arts strategies in their prekindergarten and kindergarten classrooms. The professional development program developed by Wolf Trap's project team includes annual summer institutes as well as in-classroom coaching during the school year. In the summer institutes, teaching artists in the disciplines of dance, music, and drama work with teachers in teams to develop standards based performing arts and mathematics experiences. During the school year, teachers and teaching artists work together in partnership, planning and implementing lessons in the classroom-a research-based strategy often called the artist residency model (Burnaford, 2007). American Institutes for Research (AIR) conducted a four-year evaluation of the Wolf Trap AEMDD grant project beginning in 2010 when the grant was awarded. The purpose of this evaluation was to examine the implementation of the Wolf Trap professional development program and assess its impact on teacher practice (use of performing arts strategies in particular) and students' mathematics knowledge. This report focuses on program impacts by addressing two research questions: (1) What was the impact of the Wolf Trap professional development on prekindergarten and kindergarten teachers' use of performing arts and mathematics strategies; and (2) To what extent did students in the study treatment schools demonstrate better mathematics knowledge than students in the control schools? Despite the limitations, this study produced promising evidence for the impacts of the Wolf Trap professional development program on both teaching and learning. Appended are: (1) Examples of Arts Integration Routines Observed in Classroom Observations; and (2) Statistical Models for Impact Analyses. [Although a grant number was not provided in this report, the contents of this publication were developed under a grant from the U.S. Department of Education. To view a related report "Evaluation of Professional Development in the Use of Arts-Integrated Activities with Mathematics Content: Findings about Program Implementation" see EJ1050560.]