The present research was an investigation into the design and evaluation of computer based microworlds in chemistry education. Two computer microworlds were evaluated using a multimethod approach focusing primarily upon clinical observation and interview. One of the microworlds, Atom Alchemy, had been developed prior to the study. The second microworld, Molecular Alchemy, was developed within the study. A video monitoring technique was developed to record the students using the microworlds. It was found that both computer based microworlds used in the study were useful tools in chemistry education. It was also observed that where the learning taking place was predominantly heuristic, the microworlds were very effective. However, there was mixed success where learning took place by the association of information and labels. While there are some limitations, the model upon which these microworlds were based was found to be useful in chemistry education.