This study is an empirical investigation of Ausubel's paradigm of meaningful learning, applied specifically to the learning of high school physics students. In the first phase of the study path analysis and multiple regression techniques were used to describe the Ausubelian learning variables: available relevant ideas in learner's cognitive structure, the meaningful learning set of predisposition of a learner to relate concepts meaningfully, and the extent of meaningful learning that has taken place. Several background variables were also studied for their effect on learning. In the second phase, the effects of two instructional treatments on meaningful learning and their respective interaction with two corresponding Ausubelian cognitive variables were studied. In the third phase, three retention tests were administered at intervals. The analysis of data revealed evidence for a major role of relevant cognitive content in meaningful learning. An additional factor found to be significant in the leaning process was the ability to relate ideas meaningfully. Two different instructional treatments did not significantly increase scores on a measure of meaningful learning. High scorers in measures of meaningful learning set and relevant cognitive content displayed greater initial learning and more stable retention, but not faster retroactive facilitation of the material learned. The findings of the study lend qualified support to Ausubel's model of meaningful learning. (Author/PS)