Intensification of crop and livestock production, in smallholder crop-livestock systems as well as in other intensive or extensive systems, is essential to mitigate human suffering and providing time for needed social and economic changes. Harnessing the potential of well-integrated crop and livestock systems at various levels of scale (on-farm and area wide), and that often have agro-forestry and forestry inputs, is one of the powerful entry points to address such needs, issues and opportunities. The integration of crop and livestock production systems increases the diversity, along with environmental sustainability, of both sectors. At the same time it provides opportunities for increasing overall production and economics of farming. This would reduce the preference for specialized livestock production systems, in view of their problems with environmental and economic sustainability.