The research reported here addresses 2 aspects of integrated mathematics and science instruction. First we provide insights into how middle grades teachers' characterize integrated mathematics and science instruction. Then we discuss how middle grades teachers see an integrated curriculum fitting into their teaching contexts and how these contexts reflect various educational reforms, such as "the middle school model," standards-based curriculum and standardized testing. Data were gathered through the use of an open-ended survey and face-to-face interviews with middle grades teachers. Qualitative analysis techniques were used to independently analyze the survey and interview data. The results of the independent analyses were then compared. The research findings suggest that teachers draw upon a teaming model of integration when they are in their teaching contexts, which significantly differs from the models of mathematics and science integration found in the research literature. (Contains 3 tables.)