The purpose of this publication was to identify “good practices” within different agricultural extension and advisory service institutions that have implemented the use of new agricultural innovations in improving rural livelihoods and in educating farmers to use sustainable natural resource management practices in different countries. The publication reviews the major objectives of extension systems in the agricultural development process. The four major types of objectives include: 1) technology transfer, especially for the staple food crops; 2) human capital development, especially the technical and management skills and knowledge that poorly educated farm-households need to increase farm income; 3) building social capital; and 4) educating farmers to manage natural resources sustainably. These major extension objectives are assessed under different models to draw conclusions as to the manner in which extension systems can be more effectively organized.