Although both the general public and research scientists intuitively understand the word learning, the meanings they assign to it vary. Nevertheless, there is too much concern about generalizing the meaning, and too little concern about learning context. Learning context is the internal, changing relation between individual and situation; it is the phenomenon of learning. Traditionally, research has isolated individual variables from situational variables, and has treated them externally, independent of context. Aptitude-treatment interaction research, in contrast, relates individual differences to variations in treatment. Results of different experiments will not be comparable if the context-dependent meaning of specific data on learning is not considered. (CP)