In this conceptual paper, we describe the approach in storylines that builds on principles of project-based learning and focuses on supports for making science learning coherent from the students’ perspective. In storylines, students see their science work as addressing questions and problems their class has identified. We present design principles that guide the teaching and enactment of storyline units and explore the connections of these principles to ideas of project-based science. We illustrate how these design strategies are reflected in a high school biology unit co-developed by teachers and researchers. We present student artifacts that document the agency students take on in this work. We then summarize results from earlier studies examining students’ learning and perceptions of coherence of their learning experiences.