Effectively grouping learners in an online environment is a highly useful task. However, datasets used in this task often have large numbers of attributes of disparate types and different scales, which traditional clustering approaches cannot handle effectively. Here, a unique dissimilarity measure based on the random forest, which handles the stated drawbacks of more traditional clustering approaches, is presented. Additionally, arule-based method is proposed for interpreting the resulting learner segmentations. The approach was implemented on a real dataset of users of the CareerWISE online educational environment, designed to provide resilience training for women STEM doctoral students, and wasshown to find stable and meaningful groups of users.