21st century educational reform initiatives value creativity, collaboration, innovation, and higher-order thinking (Scardamalia, 2002), the skills needed for students to successfully address the complex engineering challenges facing society. A Framework for K-12 Science Education: Practice, Crosscutting Concepts and Core Ideas (NRC, 2012) acknowledges that advances in knowledge occur through collaboration, with many minds working together to communicate and share ideas over time. It has been proposed that collaboration, creativity, and persistence are of value to engineering (Cunningham, 2012), and that engineering possesses a unique set of epistemic practices, including envisioning multiple solutions and teamwork (Cunningham and Kelly, 2017). Cunningham (2012) considers collaboration to be a hypothesized critical component of engineering, asserting that collaboration is valued and cultivated in the Engineering is Elementary (EiE) curriculum as in engineering itself. This case study examined Lesson 4 of the EiE unit An Alarming Idea: Designing Alarm Systems to look for evidence of collaboration between third grade students participating in the engineering design process. Through the analysis of video and corresponding audio of students working in small groups, this study identified specific behavior indicators of Collaboration, a term defined as including cooperative, constructive, cognitive, metacognitive and collaborative dimensions, as being present during Lesson 4. Analysis of the data revealed that certain steps of the engineering design process fostered Collaboration behaviors, as did group size, composition, adult interactions, and time spent on group work. Results of this study endorse the EiE curriculum as a mechanism for fostering Collaboration, supporting the assertion that collaboration is a hypothesized critical component of engineering valued and cultivated in the EiE curriculum.