Inadequate science knowledge of preservice teachers enrolled in science methods courses not only limits their mastery of effective teaching practices, but also may foster negative attitudes toward science teaching. This study investigated the influence of science knowledge upon attitudes toward science teaching in a one-semester elementary science methods course by embedding a videodisk-based instructional component to remediate knowledge deficiencies. Preservice teachers in the experimental group first learned core concepts in physical and earth science through a series of 24 interactive videodisk lessons and then used the concepts as a foundation for preparing and presenting model science lessons. Results showed that the experimental group overcame their initial knowledge deficiencies by mastering the core concepts presented (mean proportion correct on mastery test = 0.91), with multivariate covariance analysis confirming that the experimentals gain in science knowledge was significantly greater than comparable controls in the parallel science methods sections. Additionally, as a result of mastering the core concepts underlying earth science, preservice teachers using the videodisk instruction also displayed significantly greater confidence in their understanding of science knowledge and more positive attitudes toward science teaching at the elementary levels. Implications for improving elementary science teaching through preservice and in-service training are discussed.