We investigate aspects of reform enacted in 66 class observations from 18 institutions collected as part of the National Study of University Calculus in the US. We examined four aspects related to how problems were solved in class: the extent of student involvement, the representations and technology used, and specific features of the problems solved. As a whole, we observed low enactment of reform-oriented practices in these lessons, with more variation within rather than across institutions. We describe lessons that illustrate different ways in which reform aspects were enacted and suggest some implications for further studies.