This article describes the historical origins and development of a series of well-known study strategy inventories and seeks to identify their conceptual bases. The theories and evidence influencing the development of 6 contrasting instruments are considered before examining empirical evidence of similarities and differences between the measurement instruments. This analysis is tackled in three stages, looking first at inventories developed in the 1970s and 1980s that focused mainly on motivation, study methods, and learning processes. The more recent work that brought in mental models, metacognition, and self-regulation is then introduced, leading to a concluding section that discusses the conceptual bases of the whole set of inventories. The trends found in this research area are described and used to explore the current confusion of overlapping terms describing apparently similar aspects of learning and studying in higher education.