A major motivation for accounting research is providing evidence on how earnings are useful to a wide range of users in making economic decisions. Of particular interest over the last decade has been the issue of the quality of accounting reports, particularly the quality of earnings. This study examines Board Supervision and Earnings Quality of Listed Conglomerate Firms in Nigeria Stock Exchange (NSE) with a view to determine how board size, proportion of non-executive directors and number of board meetings have significant impact on earnings quality of the conglomerate firms under study. Correlation research design is used for the study and data is collected from six (6) conglomerate companies listed in the NSE daily official list as at 31 December 2012 from the firms‟ official website and facts books. The study covers periods 2006 - 2013. Multiple regression analysis was used as technique for analysis. All output are obtained using STATA 10 statistical package.The findings indicated that a positive relationship between Board size and earnings quality and significant at 5%level of significance. The relationship between proportions of Non-Executive and number of board meetings is positive but insignificant. The study was able to establish the overall significance relationship of the three variables with earnings quality. The study therefore, recommends an increase in Board size of the conglomerate firms so as to strengthen supervision and increased earnings quality. Also, an increase in the proportion of non - Executive Directors will enhance effective board supervision thereby leading to a higher earnings quality. Frequent meetings of the board will create immediate forum for removing gray areas that may affect supervision and earnings quality