Student achievement can be influenced by different types of educational inputs with results varying across time and context. Studies of educational inputs and student achievement in a variety of contexts can provide valuable insights into how the relationships between educational inputs and student achievement depend upon local context and specific circumstance of education. Cambodian education is distinctive with its high prevalence of community financing of education which results not by the government's deliberate policy but rather by the government's inability to meet the needs of all school-aged children. Cambodian households find that if they want schooling of a reasonable quality especially in primary school level, then they must provide much of the necessary resource. This study attempts to identify the educational inputs which make the greatest impact on student achievement using survey data from school principals, teachers, students and their parents. The study employs multiple regression analysis to build a model for the relationship between educational inputs and student achievement. The result of the analysis shows that the availability of instruction materials has a relatively large impact on student achievement.