This paper studies a partial-contracting model where an agent may provide effort to increase a project's scope before some later decisions have to be taken. Consistent with existing empirical evidence, we find a positive relationship between exogenous risk and delegation. That is, we show that only if exogenous risk is sufficiently large, the risk-neutral principal may prefer to delegate authority over decisions to the risk-averse agent. Intuitively, for incentive reasons, the principal may optimally want to allow the agent to reduce his risk exposure. Nevertheless, even endogenous risk may be higher when the risk-averse agent has control.