Over the last year and a half, the Stanford History Education Group has prototyped, feld tested, and validated a bank of assessments that tap civic online reasoning—the ability to judge the credibility of information that foods young people’s smartphones, tablets, and computers. Between January 2015 and June 2016, we administered 56 tasks to students across 12 states. In total, we collected and analyzed 7,804 student responses. Our sites for feldtesting included under-resourced, inner-city schools in Los Angeles and well-resourced schools in suburbs outside of Minneapolis. Our college assessments, which focused on open web searches, were administered online at six diferent universities that ranged from Stanford, an institution that rejects 94% of its applicants, to large state universities that admit the majority of students who apply. In what follows, we provide an overview of what we learned and sketch paths our future work might take. We end by providing samples of our assessments of civic online reasoning.