The Environmental Stewardship Scheme provides payments to farmers for the provision of environmental services based on foregone agricultural income. This creates a potential incentive compatibility problem which, combined with an information asymmetry on farm land heterogeneity, could lead to adverse selection of farmers into the Scheme and therefore reduced cost-effectiveness of the Scheme. This reduced cost-effectiveness would be represented by a systematic overpayment of farmers for the land enrolled into the Scheme, compared to the opportunity cost of production. This paper examines the potential adverse selection problem affecting the higher tier of the Environmental Stewardship, the Higher Level Stewardship, using a principal agent framework combined with farm-level data on participation in the HLS. Empirically, it is found that, at the farm level, HLS participation is negatively related to cereal yields, suggesting the existence of adverse selection in the HLS and farmer overcompensation from entering the scheme.