Sherman Diaz contributed 12 points and Ruben Guillandeaux 10 for the Explorers (9-11, 2-4 Atlantic 10), who snapped a two-game losing streak. La Salle shot 38 percent from the field, 37-for-47 from the line and outrebounded Richmond 54-25.
The Spiders struggled from the field, shooting just 19-for-58.
Richmond closed within seven points, 45-38, on a 3-pointer by Butler with 10:06 remaining. But the Explorers responded with a 12-4 run, capped by a 3-pointer by Harris, and led 57-42 with 5:59 left. Harris scored five points during the run.
Richmond never got closer than 13 the rest of the way.