This metasynthesis focused on STEM teaching and learning practices in middle and high school classrooms and in informal settings. Research artifacts between 2005 and 2012 were examined. Fifty-eight unique artifacts were classified into four categories: reform-based teaching and learning, informal education, teacher factors, and technology use. Promising pedagogical reform-based practices included inquiry-based learning, engineering design, project-based learning, problem-based learning, and hands-on practices. The most common intervention identified was increasing teacher content knowledge. Even though STEM informal activities attempt to recruit underrepresented or low achieving students, the reality is that access to informal STEM activities is often based on students’ expressed high interest, prior academic achievement, teacher recommendation, time and travel availability and flexibility, and overall levels of ambition or motivation. Positive outcomes, due to technology, appeared to covary with other factors such as teacher content knowledge, the presence of campus support, or active engagement within a learning community.