Assessment is an integral part of teaching and learning. In integrated STEM inquiry, we also have to consider how students’ learning can be assessed. Assessment in integrated STEM inquiry is unlike traditional forms of assessment, where students’ attainment of conceptual understanding is measured through robust paper-and-pencil tests or where students’ ability to carry out experiments is determined by performance tasks. In integrated STEM learning, assessment is multi-faceted and multi-level, taking the form of a suite of different assessment methods that are dependent on the nature of the activities that students engage with in the different phases of inquiry. In this chapter, we discuss the various assessment models for integrated STEM inquiry with suggestions for how each can be implemented.