This study jointly examines causal determinants and effects of Chinese foreign aid. Using novel micro data, I first document that the Chinese state's paramount goal of domestic political stability significantly influences its aid allocation decisions. In response to labor unrest in China, infrastructure aid contracts are allocated to state-owned firms in the affected areas, resulting in increased employment. Domestic unrest also affects the allocation of Chinese aid to recipient countries through connections with these firms. Finally, I exploit this granular variation to develop a novel instrument for identifying the causal effects of Chinese aid on recipients. Results show large positive short-term but small long-term effects on GDP, consumption and employment. The findings highlight the importance of domestic political considerations in shaping aid allocation and the spillover effects on recipients. *Media coverage: Project Syndicate, US-China Today, [[VoxDev]](https://voxdev.org/topic/institutions-political-economy/chinese-foreign-aid-can-self-interest-benefit-recipients)* [[pdf]](https://www.jorismueller.com/files/chinaaid_latest_draft.pdf/)
Diversity poses fundamental challenges to state-building and development. We study the effects of one of post-colonial Africa's largest policy experiments — the Tanzanian Ujamaa policy — which attempted to address these challenges. Ujamaa aimed to create a national identity and consolidate state authority by mandating a highly diverse population to live in planned villages, where children received political education. We combine differences in exposure to Ujamaa across space and age to identify long-term impacts of the policy. We show persistent, positive effects on national identity based on surveys and inter-ethnic marriages. We observe no systematic differences for cohorts that were above or below treatment-age during Ujamaa. Our preferred interpretation, supported by evidence that considers alternative hypotheses, is that changes to educational content drive our findings. Moreover, while Ujamaa contributed to establishing the Tanzanian state as a legitimate central authority, it appears to have lowered demands for democratic accountability. *[[NBER working paper]](https://www.nber.org/system/files/working_papers/w30731/w30731.pdf/)* [[pdf]](https://www.jorismueller.com/files/statebuilding_Ujamaa_latest_draft.pdf/)
This paper provides evidence of the long-run effects of a permanent increase in agricultural productivity on conflict. We construct a newly digitized and geo-referenced dataset of battles in Europe, the Near East, and North Africa from 1400–1900 CE and examine variation in agricultural productivity due to the introduction of potatoes from the Americas to the Old World after the Columbian Exchange. We find that the introduction of potatoes led to a sizeable and permanent reduction in conflict. *Media coverage: marginalrevolution.com* [[pdf]](https://www.jorismueller.com/files/Agricultural_productivity_conflict_latest_draft.pdf/)