[This paper is part of the Focused Collection on Curriculum Development: Theory into Design.] A level of curricular design, called "design tactics," is identified to fill a gap in the research literature between the broad principles that guide curriculum development and the detailed writing of specific activities and lessons. The use of design tactics is illustrated with a case study using a sequence from middle-division undergraduate electromagnetism, the ring cycle, developed as part of the Paradigms in Physics project at Oregon State University. A retrospective analysis of the curriculum development process identified ten design tactics, related to content, sensemaking, and classroom practice. Further analysis of secondary implementations at DePaul University and California State University San Marcos illustrates how design tactics can also be used to make adaptations to local settings and contexts. Design tactics can serve as a productive bridge between higher-level design principles and activity development.