Our understanding of programs is enhanced when trained, skilled, and observant evaluators go "into the field"--the real world where programs are conducted--paying attention to what's going on, systematically documenting what they see, and reporting what they learn. The article opens by presenting and illustrating twelve reasons for building fieldwork into evaluation designs. While in-depth fieldwork is the evaluation ideal, the evaluation reality is that brief site visits are the more common design. The article identifies systematic weaknesses in how site visits are commissioned and conducted, and proposes standards for improving quality and use.