SummaryChina has adopted purchase of services to facilitate the development of the societal sector, including social organisations, the social work profession and social services. Project‐based and post‐based purchases are two typical policy designs. Why do the local states develop two different designs to serve similar intentions? The answers to this question contribute to the broader discussion of policymaking and social development in China. Using the intention‐capacity analytic framework, this study systemically compares Guangzhou's project‐based model and Shenzhen's post‐based model by drawing upon an extensive review of policy and archive documents, key informant interviews and field observations. The comparative study suggests that a pro‐market ideology and incomplete analytical capacity in policy learning directed the design thinking towards market mechanism and purchase of services. Without the organisational conditions of social organisation and social work in Guangzhou, rapid growth in the social work workforce became the top priority in Shenzhen. Meanwhile, the trustworthiness of newly developing social organisations is another concern. All of these concerns underpinned the post‐based design. Both models, with substantial fiscal support, succeed in expanding the societal sectors. But the mix of market and hierarchy tools, for the post‐based model in particular, is an obstacle in further enabling social organisation and the social work profession. Copyright © 2017 John Wiley & Sons, Ltd.