Over the last several decades, Social Accounting Matrices (SAMs) have emerged as a widely accepted method for the presentation of macroeconomic data and an analytical technique for impact analyses at national, regional and village levels. Although there is a large body of literature concerning the construction and application of SAMs, there are only a few impact evaluations with regional and village SAMs. This is particularly evident when focusing on the impact of regional investment projects in developing countries. In this paper, we have attempted to demonstrate how a regional SAM can successfully be applied to evaluate the impact of an irrigation project in the Southern Province of Sri Lanka. This example clearly demonstrates the possibility of using regional and village level SAMs in evaluating post-war development projects, such as infrastructure and irrigation projects, in Sri Lanka