Models are approximations of real systems. Although, in theory, there is no limit to the refinement and detail of a mathematical model, with greater refinement allowing more detailed representation of the physical system, there is a practical limit in terms of the model outputs, which is, in part, defined by the intended end use. This chapter describes a range of collaborative model studies across a range of model complexities from simple empirical models to complex simulation models. We illustrate with several applications of agricultural greenhouse gas (GHG) models and their value to different end users. We will thus demonstrate that a range of models and approaches is often required to develop our understanding as a stakeholder community. As such, we observe that the value of a model should not be judged by its precision alone but also its utility. The need to communicate understanding to multiple stakeholders has led to a number of exciting developments in recent times. For example, although a range of common techniques are often employed with regard to process-based models, recently, there have been several exciting initiatives to expand the utility of such methods for nonexperts, with an example being the ecosystem land-use model (ELUM) discussed in this chapter.