This research was designed to examine patterns related to quality of Co-teach implementation, as evidenced by Co-teacher responses to the Colorado Assessment of Co-teaching (CO-ACT), and the usefulness of the CO-ACT in serving second purpose of predicting student academic outcomes. Participants consisted of 48 teachers (24 Co-teach partnerships) and 162 students with disabilities in grades 6-8 who were enrolled in a Co-teach class of the study’s partnerships during the 2007-08 school year. The CO-ACT examines quality of Co-teach partnerships through measurement of various factors linked to Co-teaching best practices, and provides a scoring system identifying partnerships as exemplary and non-exemplary. Student academic outcome data consisted of district-designed local assessments and statewide assessment measures. Student academic outcome data was collected and analyzed for students with disabilities in identified Co-teach partnerships. Four areas were examined in relation to the CO-ACT and its ability to predict student academic outcomes: a) whether the CO-ACT was able to predict student academic outcomes; b) the importance of the individual factors; c) the impact of the degree of Co-teacher agreement of practices; and d) analysis of these areas by subject area (math, reading, science and social studies). These four qualities were the basis for the four research questions for the study. Specifically, the aim of the study was to identify correlations among the qualities of each Co-teach partnership, and to determine whether there was a relationship between the quality of the partnership and student academic performance. Study findings indicated that in the area of math and science some CO-ACT factors were statistically significant in predicting student academic outcomes. However, when taking all study analysis into consideration, overall the results indicated that the CO-ACT did not provide statistically or practically significant predictions of student academic outcomes. Although the CO-ACT was designed to measure the presence of behaviors within a Co-teach setting that are reflected within the Co-teach literature as best practices, the exemplary or non-exemplary practices of Co-teachers did not appear to correlate with student academic outcomes. Implications of findings and recommendations for further research are discussed.