The purpose of this study is to develop a conceptual framework and a tool for measuring motivation of online learners. The study was carried out in three phases, the first of which was the construction of a framework, based on an extensive literature review. Phase two consisted of identifying variables computable from log file data, associate with the framework and compatible with previous empirical research. For this purpose, an empirical study was designed and a specific learning environment focusing on vocabulary for adults was chosen. Log files of a large population (N=2,162) were collected and variables were identified using Learnograms, a visual representation of learning variables over time. This phase resulted in seven explicitly defined variables, along with a mechanism to calculate them from the raw log files. The third phase included preprocessing of the dataset (reducing it to 674 cases) and application of hierarchical clustering of the variables. This phase resulted in thr...