You probably will not be surprised to know that a building principal is a major key to successful professional learning of science teachers. Dr. Kate McNeil and her team have done lots of great work studying professional development for building principals and also in developing tools for this specific type of professional learning. See Instructional Leadership for Science Practices.
You can also find a FREE article from the Journal of Research in Science Teaching titled Professional Development to Support Principals’ Vision of Science Instruction. This article nicely describes how principals initially engage with observing science lessons and how to connect those initial strategies to reform efforts in science instruction.
One of my favorite quotes is below. I appreciate this quote because I feel like my personal experiences working with multiple middle school and high school principals aligns with this finding.
Science for All 