This paper contrasts models of common agency in which principals compete in incentive contracts (that is, they make take it or leave it offers) with models where principals offer agents menus of incentive contracts from which the final contract is negotiated. It is shown that pure strategy equilibria in incentive contracts are robust to the possibility that principals might offer menus. In addition, a no-externalities condition is given such that any pure strategy equilibrium allocation with menus can be supported with competition in incentive contracts. The no-externalities condition is restrictive, but it is shown that it applies in most well-known common agency problems, including, for example, the Bertrand pricing problem.