Interactive-engagement (IE) techniques consistently enhance conceptual learning gains relative to traditional-lecture courses, but attitudinal gains typically emerge only in small, inquiry-based curricula. The current study evaluated whether a "scalable IE" curriculum--a curriculum used in a large course (~130 students per section) and likely adoptable by a wide range of physics departments--could produce significant attitudinal benefits relative to a traditional-lecture curriculum. This study included data across three years, 10 instructors, over 30 sections, and over 1100 students, and our analytic strategy allowed us to isolate the effects that were due to the curriculum itself rather than other potential factors such as instructor differences or preexisting differences among students. Results revealed that our Active-Physics curriculum, which is based on Moore's "Six Ideas That Shaped Physics," produced significant attitudinal and conceptual-learning benefits relative to our traditional-lecture physics curriculum. Further, the Active-Physics curriculum, for the most part, benefitted males and females equally, and relative to the Fall semester alone, the benefits of Active Physics became more robust when viewed across the entire two-semester sequence of introductory physics. Our data highlight that some (though not all) of the attitudinal benefits of small, inquiry-based courses may be achievable in larger course with scalable IE curricula that can potentially reach a large proportion of introductory physics students.