Voluntary agreements (VAs) have been widely used in environmental policymaking over the past 20 years. This paper reviews relevant theoretical and empirical literature on VAs, assessing their performance in terms of effectiveness and efficiency. Effectiveness is evaluated on three criteria: (i) effectiveness in setting the pollution abatement target, (ii) effectiveness in incentivising participation, and (iii) effectiveness in realizing the abatement target. Both static efficiency, in particular the allocation of abatement among participants in the VA, and dynamic efficiency, in particular the role of technology and informational spillovers, are evaluated. Finally, we identify gaps in the literature that provide opportunities for future research.