In the last few decades the evaluation of scientific research has become a high-stakes enterprise. With increasing political governance and federal budgets often in the billions, the livelihood of individual researchers, research groups, departments, programs, and entire institutions often swing in the balance. With its foundations in the traditional peer review system, many nations throughout the world now have large-scale systems in place for prospectively (ex ante) and/ or retrospectively (ex post) evaluating their government-financed research. This paper begins by presenting an overview of the research evaluation mechanisms in sixteen countries in terms of their primary reasons and motives for evaluating government-funded research, their basic units of assessment and core methods, and their key indicators and criteria. The paper concludes by classifying these models and mechanisms along dimensions of: (1) their basic approach to allocating or distributing research funding; (2) their general research evaluation approach or strategy; and (3) their overall quality.