Integrated science, technology, engineering, and mathematics (STEM) and project-based instruction (PBI) have both received increased attention as instructional approaches that allow for deep, authentic student learning. However, there has been little research that explores the overlap of these two related yet distinct approaches. In this case study, eight teacher-developed STEM PBI curriculum units for grades 1–8 were analyzed using content analysis methods. Each unit was scored for integrated STEM and PBI quality. Findings highlight strengths related to an authentic context for learning, opportunities for communication, and the development of a final product that is shared publicly. However, weaknesses were also apparent related to STEM content integration and learning goals, student voice and choice, assessment, and organization. Notably, the content analysis also illustrated that the units developed for elementary grades (1 and 5) were generally stronger than those units developed for middle-school grades (7 and 8). Implications for practice and future research are discussed.