Performance-based assessment is appropriate to use in a project-based, problem-based, or inquiry-based science classroom because it is consistent with the way students learn—by investigating a question or problem using tools and materials (i.e., performing an act). Since students in a project-based classroom learn by producing a product or performing an act, it is only fitting for them to be assessed using methods similar to those used to teach them—thus aligning assessment with instruction. This article provides two common examples of performance-based assessments that science teachers can use in (or adapt for) their classrooms and a discussion of their strengths and limitations.