Aspects of the invention relate to techniques for integrating optical proximity correction and mask data preparation. First mask writer instructions for a layout design are simulated to generate a mask contour. Based on the generated mask contour, first layout data for the layout design are adjusted for optical proximity correction to generate second layout data. Using the generated second layout data as mask target, the first mask writer instructions are adjusted to generate second mask writer instructions. The above process may be iterated until an end condition is met.