Contemporary peer code review is a lightweight, asynchronous, tool-supported method for ensuring the quality, maintainability, and sustainability of software. While this approach has been useful in the development of traditional software, it is underutilized in the development of scientific HPC software. Because the complexity of scientific HPC software makes testing difficult, peer code review is a good option. Under the umbrella of Software Engineering for Science https://se4science.org/ and supported by the Better Scientific Software http://BSSw.io initiative, this tutorial introduces developers (and students) to the concepts of code review and its tool support. The tutorial will begin with a general introduction to code review, a more specific discussion of the unique nature of scientific code review, and an overview of avaiable tool support. Then, tutorial attendees will participate in hands-on exercises to practice code review. We will conclude the tutorial with a group discussion about best practices for performing scientific code review.