In recent years, wireless networks have enjoyed tremendous development and popularity due to the technological advances of wireless radio devices. While interest in conventional wireless networks continues to evolve, new types of wireless networks, such as Mobile Ad Hoc Networks (MANET) and Wireless Sensor Networks (WSN) are evolving fast and receiving much attention from academia, industry, and government. Scalability and energy-efficiency present two of the most important challenges in Mobile Ad Hoc Networks. In this dissertation, we propose clustering and routing approaches to overcome scalability and energy constraint problems that exist in large scale MANETs. To handle these problems, we design a hierarchical energy-efficient scheme that can be easily setup and maintained. The scheme has three major components, namely: (1) the hierarchical (clustering) component, (2) the maintenance component, and (3) the routing component. Our research provides a mathematical formulation of the clustering component using integer linear programming - ILP. Our simulation study shows that our suggested approaches outperform well known schemes found in the literature.