The need for collaboration between researchers and practitioners to address the research-practice gap is a long-debated topic in applied linguistics. Little is known, however, about how researchers and practitioners can collaboratively develop teaching materials, as a potential venue to narrow the gap. This study explored how two groups of professionals in China worked together to develop textbook materials and achieved bi-directional knowledge flow. In addition, the textbooks were analyzed in light of how participants contributed to the co-authored product. Interviews with four researchers and three practitioners along with their written reflections revealed relatively equal and constructive collaborative relationships in which multi-directional knowledge flow, co-creation of new knowledge, and positive emotional interactions emerged. Though subtle, the collaboration was reflected on the nature of the developed textbooks. With a nuanced interpretation of the complexity of researcher-practitioner collaboration, we highlight the emotional dimension of collaboration and the need to pay attention to the person in the collaboration when examining a research-practice relationship.