This report assesses six studies relevant to immigration reform debate. It examines their methods, assumptions, strengths and limitations, and creates a framework for assessing current and future research. We found that economic impact studies agree that immigration reform will increase GDP. Fiscal impact studies, which measure the effect on government outlays and revenues, agree less. Differences in findings arise from differences in scope and time; treatment of the second generation; definition of the immigration reform scenario; modeling of the current law over time; and assumptions regarding labor force, wage growth, and the number of immigrants that will attain legal status.