This study investigates the roles of additionality of environmental benefits and spatial spillover effect of grassland conversion in determining the optimal grassland easement acquisitions. The preliminary results indicate that when conversion hazard rate is large then considering additionality and spatial spillover does not secure much additional environmental benefit than does ignoring additionality or spatial spillover. The study further explores the performance of three environmental benefit targeting strategies as well as three heuristic optimization algorithms in terms of securing environmental benefits via easement acquisition.