This study was attempted to examine gender differences in mathematics achievement andrnmathematics self-esteem and to explore some factors that contribute to this achievementrndifferences in the 2nd cycle primary schools of South West Shoa Zone .rnTo perform this study, four mathematics tests for the respective grades 5-8, twornquestionnaires one for the teachers teaching mathematics Grades5-8 in the sampled Schoolsrnand the other for 480 (240 male and 240 females) students sampledfrom six primary schoolsrnin South West Shoa Zone. The student's questionnaire includes nine mathematics self-esteemrnquestions adopted from Rosenberg (1965) self-esteem scale. A t-test, analysis of variancern(ANOVA) and Pearson correlation coefficients were employed to analyze the data. The resultsrnindicated statistically significant gender differences (a = .05 level) in mathematicsrnachievement in favor of males. As a whole the difference observed between urban and ruralrnstudents' mathematics achievement was not significant. But it was observed that it isrnsignificant between rural males and females in favor of males. In this study the factors such asrnfather 's education level, family size, family's occupation, family's help, guide and assistancerndid not show a significant impact on the achievement of students included in the study. But therndifference in mother's education level shows a significant difference in students' mathematicsrnachievement. With regard to mathematics self-esteem a significant difference was observedrnbetween male and female students in favor of males. It was also observed that there was arnsignificant positive relationship between students' positive mathematics self-esteem and theirrnmathematics achievement. Similarly, there is a negative relationship between students'rnnegative mathematics self-esteem and mathematics achievement.rnThe teacher 's expectation was found to be different with gender and it was observed that theyrnexpect better participation, performance and achievement from male students while they dornnot expect such qualities from females. It was recommended that sensitization and awarenessrnbuilding activities to enable the society, family, teachers and peers have to be done againstrnthe cultural beliefs which marginalize female students. Females who are showing specialrntalents should be encouraged and used as the role models. There should be the schoolrnguidance and counselor at the primary school so that the students could get the necessaryrnguidance and counseling from early school level and be able to develop positive self esteem inrnmathematics. Teachers should be trained in a way that they could assist, help and guidernfemale students