This study examined the differences between preservice and inservice teachers' perceptions of knowledge in instructional planning skills for teaching science in primary grades and identified the skills perceived as most knowledgeable and least knowledgeable by the two groups. Forty-one inservice and preservice African-American teachers from an early childhood program in a Midwestern urban university participated in the study. The perceptions were gathered using a five-point Likert-type scale on 10 instructional planning skills for teaching science. Multivariate analysis of variance was employed to examine the differences of perceptions across 10 specified skills in the 2 groups of teachers. Descriptive statistics were used to identify the skills perceived as least knowledgeable and most knowledgeable by the two groups. Results showed statistically significant differences between the two groups of teachers in their perceptions of the 10 skills of instructional planning for teaching science. Preservice teachers perceived that they had little knowledge in most of the skills. Inservice teachers perceived that they had considerable knowledge in the 10 skills. The findings of this study provide useful feedback to teacher education programs regarding the extent of knowledge and skills that preservice and inservice teachers will need to meet the demands of teaching science in primary grades. (Contains 38 references.) (Author/SM)