The aim of this research was to describe the effects of Think-Pair-Share strategies, used during Guided Reading lessons, on reading achievement. Think-Pair-Share is a co-operative teaching strategy that includes three components; time for thinking, time for sharing with a partner and time for each pair to share back to a larger group. The use of Think-Pair-Share unites the cognitive and social aspects of learning, promoting the development of thinking and the construction of knowledge. The strategy lends itself to inclusion within Guided Reading lessons, where the focus is on meaningful discussion around text and promotion of the use of comprehension skills and strategies to foster comprehension. The literature review describes the effectiveness of explicit comprehension strategy instruction within the context of small group discussion. Strategies that foster cooperative learning have been successful in developing interpersonal skills, cognitive skills and metacognitive awareness. There is very little research documenting the effects of the use of the Think-Pair-Share strategy. The study took place in a Year 6 classroom with two intervention groups, each containing six children. One group was reading above their chronological age and the other below. Control groups reading at these levels were also used. Three variations of Think-Pair-Share were utilised during the eight week intervention period; Predict-Pair-Share, Image-Pair-Share and Summarise-Pair-Share, and the research centred on the effects of the intervention on reading comprehension. A quasi-experimental design was employed using a pre-test, post-test format and a mix of quantitative and qualitative measures to ascertain the effects. The results confirmed the positive effects of the strategy on reading achievement, especially for those students reading above their chronological age, although an extended period of intervention may have had more significant effects on those reading below. Positive effects on aspects of oral language use, thinking, metacognitive awareness, and the development of reading comprehension strategies were noted with both of the intervention groups. Results have significance for those concerned with implementing effective literacy practice. They demonstrate the versatility of the Think-Pair-Share strategy as a tool to foster conversation, and one that can be adapted to suit the learning focus and the needs of particular groups of students.