In this chapter two examples are presented that demonstrate the added value of integrated ecological-economic modelling. Both examples consider market-based conservation instruments, the first analysing the impact of the agglomeration bonus on the coexistence of two competing species, and the second analysing the dynamics and cost-effectiveness of output-based payments that reward the presence of a species on the land. The second example involves a feedback loop between ecological and economic system components that is analysed in detail. It is shown that the feedback loop increases the uncertainty in the system, which implies that the performance of the payment scheme is uncertain. This uncertainty is then addressed by a co-viability analysis to derive trade-off curves between the certainty of achieving a desired ecological outcome (keeping the population size above a specified target) and the certainty of achieving a desired economic outcome (keeping scheme costs below a specified limit).