The use of machine learning techniques to automatically analyse data for information is becoming increasingly widespread. In this paper we examine the use of Genetic Programming and a Genetic Algorithm to pre-process data before it is classified by an external classifier. Genetic Programming is combined with a Genetic Algorithm to construct and select new features from those available in the data, a potentially significant process for data mining since it gives consideration to hidden relationships between features. We then examine techniques to improve the human readability of these new features and extract more information about the domain. Categories and Subject Descriptors I.2.2 [Artificial Intelligence]: Automatic Programming – Automatic analysis of algorithms, Program modification, Program synthesis, Program transformation, Program verification. General Terms Algorithms, Performance, Experimentation, Human Factors. Keywords Genetic programming, genetic algorithm, feature const...