The Bourbon monarchs who ascended the Spanish throne in 1700 attempted to reform the colonial system they had inherited, and, in particular, to make administration more efficient and cost-effective. This book analyses one aspect of the Bourbon reforms, which was the efforts to transform frontier missions, to make the missions more cost-effective, and to accelerate the integration of indigenous peoples in northern Mexico to European cultural norms. In some instances, the Crown had funded missions for more than a century, but with minimal results. The book attempts to show how the mission programs changed, and what the consequences – especially demographic – were for the indigenous peoples brought to live on the missions.