While integrating engineering into science education is not new in the United States, technology and engineering have not been well emphasized in the preparation and professional development of science teachers. Recent science education reforms integrate science and engineering throughout K-12 education, making it imperative to explore the conceptions teachers hold of engineering as a discipline, and as an approach to teaching. This analysis draws on focus group interviews with practicing secondary teachers (n = 12) conducted during a professional development seminar. The goals of the seminar were to present engineering as a heterogeneity of practices and inquiries organized to solve human problems; and, to model design-build-test pedagogy as a new approach to teaching. Outcomes show teachers' conceptions of engineering as a discipline are that it redefines failure as necessary for success, and that it can more directly link school learning to serving society. Teachers also anticipated that design-build-test pedagogy would disrupt procedural learning in science, and likely invert which students achieve and why. These outcomes are discussed in light of reform goals, particularly as regards issues of equity. Implications for science teacher educators are also discussed.