Co-culture of chondrocytes and mesenchymal stromal cells (MSCs) has been shown to be beneficial in engineering cartilage tissue in vitro. In these co-cultures, MSCs increase the proliferation and matrix deposition of chondrocytes. The MSCs accomplish this beneficial effect by so-called trophic actions. Thus, large cartilage constructs can be made with a relatively small number of chondrocytes. In this chapter, we describe different methods for making co-cultures of MSCs and chondrocytes. We also provide detailed protocols for analyzing MSC-chondrocyte co-cultures with cell tracking, proliferation assays, species-specific polymerase chain reactions (PCR), rheological analysis, compression analysis, RNA-sequencing analysis, short tandem repeats analysis, and biochemical examination.