This study assesses the level of implementation of Enterprise Risk Management (ERM) in companies listed in the Nairobi Stock Exchange. The study also seeks to test the significance of factors affecting this level of ERM implementation and to investigate whether the level of ERM implementation has a positive effect to the value of companies as measured by Tobin’s Q. Data was collected from a sample of 22 companies listed on the Nairobi Stock Exchange (NSE) for the periods ended December 2009. The research findings show that most of the organizations sampled viewed ERM implementation as a strategic business initiative as compared to a compliance requirement. The study also finds that there is a significant relationship between the appointment of a Chief Risk Officer and the level of Enterprise Risk Management Implementation in companies. However, it does not find a significant relationship between the level of ERM implementation and the following variables; industry of operation, level of board independence, size of the firm, and growth rate of the firm. The results of this study show that an increase in the level of ERM implementation in companies had a positive contribution to the value of the companies.