Marketing Science analyzed web traffic data from 303 mainstream publisher websites in June 2017 to directly measure ad blocking rates. They found: 1) Ad blocking on mobile web was 0% in the U.S., unlike industry estimates of 35%. 2) Mainstream publishers saw lower ad blocking than estimates, with a range of 6-14%. 3) Measurement within ad frames corroborated a 0% ad blocking rate, as ads are not supposed to load when blocking is active.