This document describes a study that used genetic programming to develop an accurate classifier for detecting pulmonary nodules on CT scans. The proposed method involved segmenting the lungs, detecting nodule candidates, extracting features, and using genetic programming to evolve a combination of features and functions to classify nodules versus non-nodules. When tested on 153 nodules across 32 CT scans, the genetic programming classifier achieved a sensitivity of 92% and specificity of 86%.