The Science Teachers Learning from Lesson Analysis (STeLLA) project is a videobased analysis-of-practice PD program aimed at improving teacher and student learning at the upper elementary level. The PD program developed and utilized two "lenses," a Science Content Storyline Lens and a Student Thinking Lens, to help teachers analyze science teaching and learning and to improve teaching practices in this year-long program. Participants included 48 teachers (n = 32 experimental, n = 16 control) and 1,490 students. The STeLLA program significantly improved teachers' science content knowledge and their ability to analyze science teaching. Notably, the STeLLA teachers further increased their classroom use of science teaching strategies associated with both lenses while their students increased their science content knowledge. Multi-level HLM analyses linked higher average gains in student learning with teachers' science content knowledge, teachers' pedagogical content knowledge about student thinking, and teaching practices aimed at improving the coherence of the science content storyline. This paper highlights the importance of the science content storyline in the STeLLA program and discusses its potential significance in science teaching and professional development more broadly. (Contains 5 figures, 3 tables and 1 note.)