||Climate variability and change is projected to increasingly affect smallholder farming systems in southern Africa and the maize value chain will particularly suffer from the late onset of and more erratic rainfalls. Heat stress will further affect maizebased cropping systems as temperature is projected to increase by 2.12.7°C. Based on CSA practices, prioritized in national and regional workshops, a study was conducted using historical data collected by the International Maize and Wheat Improvement Centre (CIMMYT) and its national partners to better understand the benefits and challenges of CSA technologies and to assess their feasibility for a large out scaling initiative in southern Africa. The specific objective of the study was to assess their economic, biophysical, environmental and social benefits using existing available long term data. For completeness a summary of challenges in their implementation was also provided. The study was carried out in target areas of Zambia, Malawi and Zimbabwe where such longterm data existed. The CSA technologies under survey were mostly conservation agriculture (CA)based interventions as this was the only longterm data available. All sites had at least two CSA comparisons and a conventional control practice which was considered not climatesmart. Maizebased cropping systems consisted of other complimentary CSA practices e.g. rotations with legumes and agroforestry species, droughttolerant maize varieties, targeted application of fertilizer and manure amongst others, which were however not the primary focus of this study. Based on partial budget conducted for all the areas, the results showed positive economic indicators for most CSA practices in form of a positive Net Present Value (NPV) and a greater Internal Rate of Return (IRR), which was greater than the discount rate. All the prioritized CSA options required at least a year to provide economic returns (increased productivity and income) as reflected by the payback period. In Malawi the CAmaize/legume intercropping treatment had the greatest NPV, IRR, Return on Investment (ROI), Return on Labour (ROI) as compared with the conventional practice. In Eastern Zambia, the CAmaize/legume intercropping treatment was the most profitable manual systems, whereas the rip line seeded CAmaizelegume rotation was the most profitable animal traction system as compared to the conventional practice. In Zimbabwe the CAripline seeded maizelegume rotation was again the most profitable practice while direct seeding was more profitable in southern Zambia. The biophysical benefits have been greatest in system comparisons in Malawi and in southern Zambia. CSA systems outyielded the conventional control in most cases and in some it reached more than 60% yield gain. The benefits were usually more consistent, the longer the CSA practice was applied. The benefits in the CSA systems practiced in Eastern Zambia and Southern Zimbabwe were less obvious, mostly due to the relatively short duration of implementation, variability between farm sites and unpredictable weather events (floods and droughts) at the respective sites. Overall, at all sites averaged, there was a clear positive yield benefit across sites and seasons when comparing CSA practices with conventional control treatments. An additional regional study across many agroecologies clearly show increased resilience against heat and drought stress especially on sandy and loamy soils. Yield benefits under CSA management are likely a response of improved soil quality which is a result of notillage, residue retention and crop rotations and additional complimentary practices implemented at the sites. CSA systems increased water infiltration which translated into increased soil moisture during the cropping season. The CSA systems also reduced soil erosion and increased soil carbon at some sites. Supporting soil quality data were derived from strategically located onstation trials where soil carbon and erosion measurements were possible. The data from onfarm soil carbon measurements, which is currently been summarized, will further support the results of this study. Social benefits of CSA included reductions in farm labour for weeding and planting which preferentially benefit women and children. Labour benefits for planting were dramatically reduced specifically in Malawi where farmers practice ridge and furrow land preparation as the conventional control practice and where weed control is manual with a hoe. Direct seeding and weed control with herbicides could potentially reduce the labour burden on women and children by 2545 labour days. In addition, the more diversified diet resulting from rotations and intercropping systems with legumes greatly benefitted livelihoods as they improve the nutrition of smallholders in the households. Challenges in the implementation of a range of CSA practices have been documented and require some adaptive and participatory action. However these challenges are surmountable and will enable cash constraint and risk averse farmers to adopt climatesmart options. We conclude that CSA practices provide substantial financial and biophysical benefits which often increase over time. These translated into environmental and social benefits for smallholder farmers which is the base for a strong business case for scaling.