With the adoption of content and practice standards across STEM subject areas in PK-12 school settings in the U.S., out-of-school learning sites such as museums, youth-based makerspaces, and afterschool programs have questioned their role in engaging youth as STEM professionals during making-related activities; forming a bridge between the two worlds – in-school and out-of-school learning contexts. We have previously attempted to measure youth engagement in science and engineering practices (Simpson et al., 2017), but found the NGSS Science and Engineering practices to be limited for evaluating informal settings. Our current instrument is a bit broader in scope and provides a tool for educators, evaluators, and/or researchers to measure observable indicators of youth engaged in practices common to professionals across science, technology, engineering, and mathematics (NRC, 2012). We utilized established PK-12 process skills within the United States as the foundation of the observational tool (e.g., Standards for Mathematical Practice in the Common Core State Standards (CCSS, 2010)). Similar practices are also visible globally such as in countries across Europe (Education, Audiovisual and Culture Executive Agency 2011). Although these standards-based documents frame engagement with these practices within a formal setting (e.g., school classroom), we have found evidence of youth enacting these practices within an informal STEM-related making and tinkering setting (Simpson et al., 2017). Our findings highlighted how enactment of these practices “looked” differently than one might expect in a formal setting. We also found instances of youth engaged as STEM professionals not explicitly stated within the parameters of these standards-based documents such as experiences with failure. We built upon our understanding from this study to create an interdisciplinary tool of 11 STEM practices. The suite of instruments include (1) an observation tool, (2) a survey, (3) a peer-to-peer interview protocol, and (4) a tweet-wall.