This paper analyses challenges and opportunities for improving energy efficiency in small and medium enterprises (SMEs) by reviewing research design and results out of seven European projects: SPEEDIER, SMEmPower Efficiency, E2Driver, Innoveas, Triple-A, DEESME and ICCEE. These projects aim to improve SMEs’ awareness of energy efficiency and support an effective decision-making-oriented approach to it. Drivers and barriers to energy efficiency improvements in European SMEs of various industrial sectors have been investigated by means of surveys, focused group discussions and interviews. A meta-analysis of the results of the seven EU projects was carried out to discover trends related to energy efficiency in European SMEs; this was supported by the use of a unifying analytic framework that enabled merging and cross-validation of the findings of the seven projects. The analysis indicated, by means of new data collected by the seven projects, that staff training, facilitation of energy audits, development of corporate policy measures and collaboration between SMEs involved in the same supply chain are key mechanisms to improve the uptake of energy efficiency measures in SMEs which has significant potential to achieve higher energy savings and energy cost reductions.