This study investigated the effects of using two microcomputer games to help children in grades 4 to 6 develop and apply concepts of probability. To achieve the object of the games, a player should choose moves ("captures") so that the probability of recapture by an opponent is minimized. Questions addressed included whether students develop understanding of this application of probability concepts as a result of experience playing, whether they develop this understanding as a result of discussing the games with an adult, and whether transfer occurs from one game version to another. Data were collected from interviews conducted with the children as they played the games. Among the data analyses were measures of the children's use of four known strategies and measures of the congruence between their statements about their srategies and their actual play. Results indicate that some subjects had little difficulty applying probability concepts and explaining their strategies; others recognized that some positions changed hands more than others, but did not seem able to relate this to probability. Based on these and other results, it was concluded that the games are suitable activities and that discussion of them is valuable. (Author/JN)