Zoning is a widely used tool to manage residential growth. Estimating the effect of zoning on development, however, is difficult because zoning can be endogenous in models of land conversion. We compare three econometric methods that account for selection bias in a model of land conversion: a jointly estimated probit-logit model, propensity score matching, and regression discontinuity. Our results suggest that not accounting for selection bias leads to erroneous estimates. After correcting for selection bias we find that zoning has no effect on a landowner's decision to subdivide in a rural Wisconsin county.