Market System Dynamics (MSD) and Constructivist Market Studies (CMS) have both emerged to return markets to the center of marketing thought. Arguing that the two fields have only rarely engaged in intellectual exchange, we compare MSD and CMS and consider the potential for their cross-pollination. We first outline the intellectual origins of the two fields and show how they have, in part, been propelled by three overlapping concerns: (1) market ontology, (2) market ideas, and (3) market agency. We then compare how MSD and CMS have pursued these concerns differently. Whereas MSD tends to treat markets as meaning-based, shaped by big cultural ideas and animated by institutional agents, CMS typically portrays them as practice-based, shaped by small technical ideas and animated by socio-technical agents. Based on these differences, we offer some suggestions for how the two fields may learn from each other in pursuing the three concerns in question.