The mathematics-education community stresses the importance of real-world connections in teaching. The extant literature suggests that in actual classrooms this practice is infrequent and cursory, but few studies have specifically examined whether, how, and why teachers connect mathematics to the real world. In this study, I surveyed 62 secondary mathematics teachers about their understanding and use of real-world connections, their purposes for making connections in teaching, and factors that support and constrain this practice. I also observed 5 teachers making real-world connections in their classrooms and I conducted follow-up interviews; these qualitative data are used to illuminate findings from the survey data. The results offer an initial portrayal of the use of real-world connections in secondary mathematics classes and raise critical issues for more targeted research, particularly in the area of teacher beliefs about how to help different kinds of students learn mathematics.