In most of the contract theory literature, contracting costs are assumed either to be high enough to preclude certain forms of contracting, or low enough to permit any contract to be written. Similarly, researchers usually treat renegotiation as either costless or prohibitively costly. This paper addresses the middle ground between these extremes, in which the costs of contracting and renegotiation can take intermediate values and the contracting parties can themselves influence these costs. The context for our analysis is the canonical problem of inducing efficient relation-specific investment and efficient ex post trade. Among our principle results are: (i) The efficiency and complexity of the initial contract are decreasing in the cost t...