Early mastery of reading fundamentals is essential. However currently there is a debate on the best way to teach reading. Across the US schools are choosing to use varying forms or reading curricula aligned with different pedagogies. However, not all curricula are based in empiral science. This study compares two approaches to supplementary reading instruction: guided reading and explicit phonics. A randomized controlled design was used, and first grade students were assigned to receive either explicit phonics or guided reading intervention three days per week for approximately thirty minutes each lesson. Reading fluency and a broad reading measure served as dependent variables. Results indicated that explicit phonics instruction was more effective than guided reading for students reading below grade level but was not more effective than guided reading for above grade-level. Significant results were not found for broad reading.