This study focused on accelerating development of science knowledge and understanding at the primary level (grades 1-2) as a means for enhancing reading comprehension (i.e. early literacy). An adaptation of a grade 3-5 cognitive-science-based, instructional model ("Science IDEAS") that integrated science with reading and writing, this year-long study implemented daily 45-min instructional periods emphasizing in-depth, cumulative learning of science core-concept "clusters" while integrating science and literacy in a manner that provided teachers with a thematic focus for all aspects of instruction. Results (a) confirmed the feasibility of implementing the integrated, in-depth science model at the primary level and (b) showed that experimental students obtained significantly higher achievement on Iowa Tests of Basic Skills Science and Reading tests than comparable controls. Discussed are curricular policy implications for increasing the instructional time for content-area instruction at the primary level.