The document presents a framework for studying the optimal design of contractual property rights. It discusses how property rights determine parties' outside options in economic interactions and impact efficiency and investment incentives. The framework models an interaction where a property rights holder participates in a trading mechanism. The optimal property right balances ex-post inefficiency and hold-up problems arising from the planner's inability to commit. The paper contributes by characterizing the optimal right from a non-parametric class of options and provides a foundation for why option-to-own contracts are attractive.