Design form choices and information visualization outcomes remain inexhaustible, and they result from ongoing judgments about their appropriateness or effectiveness. Visualization design decision models have been widely proposed and applied. However, experts fail to explicitly study using design judgment to produce informed, professional decisions. In this dissertation, I bridge design form informational judgment gap when analyzing five studies with lab and in-situ designs individually as well as cross-case synthetically and comparably to examine the design judgments of all students working with visualization projects. The outcome stands to explain comprehensively how these student designers make judgments throughout their design process. Through analyzing several design cases, I identify the judgments enabling design moves forward and outcomes. The findings provide a robust description of designers’ design judgment activities and how the design judgment methods relate to design outcomes. These findings may also help identify gaps in information visualization education.<br>