The objective of this study was the evaluation of the socio-economic consequences of various emission reduction targets – if set at country level – in Bulgaria and Romania. Due to the current political debate about an EU-wide 40% emissions reduction target for 2030, our analysis focused on this 40% goal. At the macro level, we analysed the effects of a least cost contribution of both countries to such an EU wide emissions reduction target and its trajectory. In order to investigate the socio-economic consequences of various emission reduction targets, we used two main approaches. We used a Top-Down approach for a macroeconomic analysis of potential investments into renewable energies and energy efficiency activities, which we complemented by a Bottom-Up approach focused on a number of mitigation measures and their potential impacts and barriers to implementation. The top down approach is based on the GEM-E3-NMS model which has been used to quantify the adjustment of the economic and energy system of Bulgaria and Romania when an EU wide target of 40% compared to 1990 is imposed in 2030.