Our multiple case study addresses the lack of opportunities many people have developing positive identification with STEM (science, technology, engineering, math) fields by investigating STEM identity authoring in three intergenerational collaborative partnerships. Adult and teen partners participated in two-day workshops learning conservation science and geospatial technologies to design and implement community projects. Our research examined how the design and implementation of intergenerational projects provided opportunities to: (1) demonstrate competence in STEM knowledge and understandings, (2) participate in performances of STEM practices, and (3) be recognized for competence and performances in STEM fields. Qualitative methods were used throughout. Data consisted of field observations followed by separate semi-structured interviews with each partner. Artifacts such as presentation posters, online maps and websites, educational materials (e.g., pamphlets and booklets), email, and forum posts were used as secondary data sources. We found STEM identities were promoted in intergenerational collaborative partnerships when personal resources and conservation science competences and performances were positively recognized by meaningful others. Our findings inform how informal STEM education programs can foster positive identification with STEM fields that may lead to increased participation in STEM pursuits across the lifespan, and likely have similar implications for formal STEM learning as well.