STEM Pathways is a partnership between five informal STEM organizations--The Bakken Museum, Bell Museum of Natural History, Minnesota Zoo, STARBASE Minnesota, and The Works--with the Minneapolis Public Schools (MPS) and the Minnesota Department of Education (MDE). The purpose of this collaborative effort is to raise the access, enthusiasm, and academic achievement of young people in STEM and their preparation for future STEM careers through a deliberate and interconnected system of STEM learning opportunities. Further, STEM Pathways tests a model for collaboration and its potential for expansion and replication across more grade levels, schools, organizations and communities. As part of a three-year pilot project, STEM Pathways partner organizations (informal STEM education organizations working with MPS and MDE) began the first year in 2013-14 with an intensive collaboration process to learn about each other's programs, make concept and theme connections, develop shared tools and strategies, and plan for project implementation. STEM Pathways began offering activities to fourth- and fifth-grade students at six MPS elementary schools in 2014-15 and continued in 2015-16. A core component of the STEM Pathways project is ongoing evaluation to inform programming as well as future efforts for the STEM Pathways collaborative. STEM Pathways participates in rigorous, independent evaluation conducted by Wilder Research during the three-year pilot project. Evaluators assess the implementation and outcomes of the project using a student survey, small-group interviews, academic data, a teacher survey, and interviews with MPS leaders and STEM Pathways partner representatives. This report summarizes outcome findings from student surveys and academic data over the two years of program implementation (2014-15 and 2015-16), as well as evaluation findings from data collected through surveys and interviews with students, MPS teachers and leaders, and partners during the second program implementation year. [Funding from Department of Defense STARBASE and Boston Scientific supported the evaluation and the project coordination throughout the three-year STEM Pathways project. Pentair Foundation provided additional funding to support the project in 2016. For "2014-2015 STEM Pathways Evaluation: First-Year Results of an Informal STEM Education Partnership, in Conjunction with Minneapolis Public Schools and Minnesota Department of Education," see ED619424.]