This paper and the associated keynote presentation review several topics that show how stormwater monitoring has been critical in the development of stormwater quality models. The first example is a timeline of how street cleaning was originally conceived as a stormwater quality control and how subsequent focused monitoring enabled a more accurate representation of its benefits. The next example illustrates scaling issues in monitoring and how data have been used to verify appropriate extrapolations of the information. Finally, a short summary of emerging contaminants of current interest illustrates the need for expanded monitoring to understand these little understood stormwater constituents and how they can be modeled to predict their sources, transport, controls, and fates. Many other topics relating to monitoring and modeling exist obviously, but these examples, mostly from the author’s publications, illustrate the range of some of these issues needing further monitoring and model development. The examples shown are only a small portion of the data collected during the referenced studies, and the full reports should be consulted for further information