The present paper aims to contribute to the literature on the foundations of incomplete contracts by providing conditions under which simple delegation of authority is the solution to the complete-contracting problem of the parties. We consider a hold-up framework where both parties profit from an investment that raises the value of an asset. Delegation turns out to be optimal if (i) the decision-dependent parts of the payoffs of the parties are linear in the asset value, and (ii) decisions have no investment-independent effect. If overinvestment might be an issue, delegation, however, with restricted competencies is optimal if some additional continuity requirements are met.