This report presents a study of bike boxes at 10 signalized intersections in Portland, OR. Boxes were installed to increase cyclist visibility and reduce conflicts with motor vehicles (MVs). Before and after video were analyzed for seven intersections with green boxes, three intersections with uncolored boxes, and two control intersections. User perceptions were measured via surveys of relevant cyclists and motorists. Both observations and motorist surveys found a high rate of compliance and understanding of the markings. Most stopping MVs did not encroach into the bike box. Both MV and bicycle crosswalk encroachment fell significantly at the box locations. Bike boxes had mixed effects on MV encroachment in the bike lane. Observed conflicts at box locations decreased, while the right turns increased. Observations found an improvement in MVs yielding at the bike box locations. Surveys found the majority of both motorists and cyclists thought the boxes made the intersections safer.