In today’s highly competitive environment, characteristics of boards of directors and CEOs are significant for firm survival and success. This research constructs a comprehensive set of board and CEO characteristics to examine their impacts on firm value using the data of non-financial listed firms in the Stock Exchange of Thailand from 2001 to 2005. It broadens the literature in economics, finance and organization and management theories. The first essay analyzes how a board is structured and who constitute a board, and investigates the importance of board diversity and network. The main results show that board diversity in age and study majors, and alumni network are favorable to firms, while diversity in educational levels is negatively associated with firm value. In the second essay, we ask what characteristics of the most important person in managing a firm determine firm value. We find that business expertise and alumni network of CEOs add value to firms, while the costs of having old CEOs outweigh its benefits. Overall, knowledge and expertise of both directors and CEOs appear to be a major determinant that contributes to higher firm value. In addition, in emerging economies, networks of key corporate personnel are significant institutional characteristics, which bring advantages to firms and enhance firm value. Our findings also support the benefits of having a smaller board. The main implications of our research are to provide evidence for relevant policy makers to improve corporate governance practices, in particular boards of directors, and for firms to develop their human resources, i.e., CEOs.