Manipulatives have been found to be effective in increasing mathematics achievement when they are put to good use (Canny, 1984; Clements & Battista, 1990; Clements, 1999; Sowell, 1989; Suydam, 1984), but their use in mathematics instruction is not clear and it is often debated to be effective (Ball, 1992; McNeil & Jarvin, 2007). The present study was an attempt to investigate efficacy of manipulatives in facilitating understanding of probability concepts in pre-service teachers. Twenty-five pre-service teachers, enrolled in a probability class, received intervention using manipulatives to promote learning of two key concepts--conceptualizing probability, and understanding theoretical and experimental probability. A pretest-posttest design was employed, and the results revealed efficacy of manipulatives, used as a tool, in promoting learning of the probability concepts. The participants reported that the probability lessons using manipulatives assisted in academic and emotional progress by being informative and useful in addition to an enjoyable experience. The features that may have contributed towards the success and educational implications of the findings are discussed.