The 2013 Human Development Report recommends the need to strengthen regional integration and South– South cooperation as part of measures to harness the wealth of knowledge, expertise, and development thinking in the South towards achieving more robust growth and development of the developing countries. Past experiences of many African countries with globalization and trade, however suggest the need for caution and that actions need to be much more informed. Against this background, this study examined the role of international trade and economic integration as well as quality of governance and public/private investment in explaining the wide differences in agricultural productivity growth performance among countries in SSA between 1990 and 2010. The study was based on a panel data on 42 countries in SSA over the period 1990 – 2010. The study was undertaken within the combined framework of neo-classical and endogenous growth theories. Agricultural Labor Productivity (ALP), measured as agricultural value-added per economically active person in agriculture, as well as Malmquist index of agricultural Total Factor Productivity (ATFP) generated by Data Envelopment Analysis, were subjected to neo-classical convergence tests, with influence of various factors on productivity growth assessed within the framework of panel data econometrics in which influences of country specific unobserved heterogeneity were controlled. The study evidences support the need for substantial capital deepening and increase public expenditure to enhance access to infrastructure, strengthen agricultural institutions and support domestic food production as key measures needed to significantly raise agricultural productivity in SSA. In addition, the study identified increased integration into African economies that are yet to be part of any regional economic integration group as well as with the Multilateral Free Trade area between Australia and New Zealand as those with significant and positive impacts on ALP and TFP in SSA respectively. The study thus recommend, support for the ongoing efforts by the African Union (AU) to harmonize policies of various regional economic groups in Africa into forming an African Economic Community with unified trade policies among member state is the right direction to move Africa forward. It also recommends the need for each country to adopt measures appropriate protect the domestic agriculture against unduly stiff competition from better supported and sometimes subsidized agricultural products from the more developed nations as short-medium term policy measures to enhance the ongoing recovery from past neglects.