This paper defines correlation, describes the Mix It Up program, discusses the teachers' beliefs about the value of correlating mathematics and science prior to program participation, and identifies problems teachers associated with correlation before and during the program. Teachers' beliefs about the value of correlation and about the problems associated with correlation are based on results from both quantitative and qualitative methods used to evaluate the program. Results indicate that teachers believe correlating mathematics and science strengthens students' content knowledge in mathematics and science, bridges the gap between mathematics and science, enhances motivation, and increases students' flexibility in problem solving. Additionally, the areas identified by teachers to be most problematic were time, planning for instruction as a team, and exposure to correlation in the past. The most important finding from the program evaluation indicates that although teachers did not identify content knowledge weaknesses before participating in the program, they did recognize gaps in their own content knowledge during program participation, and more importantly they made connections among these gaps, classroom instruction, and their own students' performance in mathematics and science.