Improved tools are required to deliver good information for decision-making on the potential socio-economic benefits of a transition to a low-carbon society. This article reports on modelling approaches to answer policy-relevant questions carried out research teams in Brazil, Chile, Colombia, Peru and South Africa. The teams link detailed models of sectors with economy-wide models and report methodological findings. Combining bottom-up and top-down models holds the promise of addressing short and long-term time-frames technological change, economy-wide interactions, direct costs, emissions reductions, and broader socio-economic implications of mitigation. While making different choices of models, common challenges were identified around: communication between the two models; treatment of time; convergence criteria; trade-offs between model accuracy and requirements of stakeholder process...