This paper describes the results of a qualitative study using ground theory to investigate the different approaches used by chemists when answering open-ended problems. The study involved undergraduate, industrialist and academic participants who individually answered three open-ended problems using a think aloud protocol. Open-ended problems are defined here as problems where not all the required data are given, where there is no one single possible strategy and there is no single correct answer to the problem. Analysis of the qualitative data identified a limited number of different approaches used to solve open-ended problems. These approaches were applied to individual participants and these were collated to identify approaches used by each group. The relative quality of solutions developed by each group was also analysed. Analysis showed that undergraduates adopted a greater number of novice-like approaches and produced poorest quality solutions, academics exhibited expert-like approaches and produced the highest quality solutions, whilst industrial chemist's approaches are described as transitional.