Our project to embed formative student assessments in the Foundational Approaches in Science Teaching curriculum required a close collaboration between curriculum developers at the Curriculum Research & Development Group (CRDG) and assessment developers at the Stanford Educational Assessment Laboratory (SEAL). This was a new endeavor for each organization, and throughout the project, many lessons were learned about embedding assessments and about the collaboration process. In this article, we discuss what we learned about the strengths and weaknesses of the collaboration up to the beginning of the randomized experiment. What we found comported with the literature on research collaborations. For example, past collaborations between CRDG and SEAL facilitated moving the project forward and sustained the collaboration. That said, the physical distance between the groups gave rise to some misunderstandings and led to a commitment to meet face-to-face on a regular basis; we found that conferencing software did not suffice. Moreover, in our zeal to implement formative assessments, the voices of teachers and teacher trainers got muffled until a pilot study confirmed their advice.