This study investigates the effects of corporate monitoring mechanisms on firm performance and their substitution and complementary effects under different conditions of agency conflict. Following the much-reported collapses of publicly listed companies such as Enron, World Com, HIH and One. Tel, corporate monitoring is an issue that has emerged at the forefront of the debate on corporate responsibility. The separation of ownership and control in publicly owned firms has the potential to create conflict between the interests of managers and shareholders. Such conflict can be reduced by devising effective monitoring mechanisms.