This study contributes to the understanding of long- and short- term determinants of cooperation among water users. We experimentally investigate the potential of water users self-governance in enhancing their contributions to a common pool as opposed to external regulation. Our focus is on the irrigated areas of Kazakhstan and Uzbekistan. Due to their Soviet past, these countries have a reputation for low bottom-up cooperation potential. Based on the different pre-Soviet irrigation traditions of the two study sites, we assess the effectiveness of short-term incentives compared to long term cultural factors of cooperation. History might matter, but we find it does not predetermine the success of current water decentralization in ancient as compared to relatively recently established irrigation sites. We find that external regulation, in fact, decreases farmers cooperation, whereas face-to-face communication increases it. This finding calls into question the top-down approach prevalent in current water policies of the region. Moreover, it suggests the viability of endogenous cooperation and hence encourages the implementation of truly self-governed water management policies in Central Asia. However, the substantial heterogeneity in individual contributions apparent at the village level also signals a warning that one-size-fits-all approaches to local cooperation are unlikely to succeed. Acknowledgement : This study was conducted in the framework of a research project Institutional change in land and labour relations of Central Asia s irrigated agriculture . The research project is funded by the VolkswagenStiftung within the funding initiative "Between Europe and the Orient A Focus on Research and Higher Education in/on Central Asia and the Caucasus".