A corelational research design was employed to examine if a relationship exists between organizational school climate and student achievement in Ethiopia secondary schools setting, and to investigate whether the various elements of school climate have independent effects on student achievement. Organisational climate was measured using the School Climate Index (SCI) developed by Tschannen-Moran, Parish and Dipaola and student achievement was measured by students' test scores at the Ethiopia General Education Leaving Certificate Examination (GELCE) in the year 2014/15. A total of 32 schools, 973 teachers and 14882 students were involved in the study. Descriptive statistics such as mean and standard deviation, Pearson r correlation coefficient and multiple regression analysis were applied for the data analysis. The results indicate that school climate has a significant and positive relationship with student achievement in Ethiopia secondary schools, but nonetheless, a weak one. The collegial leadership, teacher professionalism, and academic press were significantly and moderately correlated to students' achievement while the community engagement sub scale was not. The four factors used both for the SCI as predictor variables in the regression model were shown to have a significant relationship with student achievement when viewed as a whole, but they generated more varied results when examined individually. Teachers' professionalism is the most positive predictor of student achievement in Ethiopia secondary schools. Similarly collegial leadership and academic press are also found to be significant predictor of academic achievement. This study found no independent effect of community engagement on student achievement. It is recommended that school leaders should design school improvement plans that entail the school climate construct. School leaders need to find ways of including the community in the life of the school and foster positive relationships with the community. Principals in particular need to be mindful that the climate of a school affect achievement and the former can be enhanced to improve results.