Sophomore wing Chauncey Gilliam (Columbia, Md.) added 18 points, 16 in the first half when he went a perfect five-of-five from field, who trailed only by two (35-33) at the half.
UMBC took a brief 37-35 lead on back-to-back driving layups by De La Rosa, but the visitors went on an 11-2 run to take control, 46-39, with 15:09 remaining.
The Retrievers were within, 59-55, with 7:36 to play, but the Quakers scored the next nine points to lead comfortably, 68-55, with 5:27 remaining.
Penn hit a UMBC opponent-high 13 three-point field goals, converting 54 percent (13 of 24) from behind the arc. The Quakers entered the game shooting 30 percent from three-point range. Penn also converted 18 of 20 second half free throw attempts and were 21 of 26 (80.8%) for the evening.
Both teams hit 50 percent from the floor, with UMBC hitting 25 of 50 attempts, while Penn was 24 of 48. But the Quakers badly outrebounded UMBC, 35-21, and outscored the Retrievers, 14-4, on second chance points.
Sophomore guard Zack Rosen led four Quakers in double figures with 28 points, hitting eight of 12 shots from the field.
De La Rosa added five assists and did not commit a turnover in 34 minutes of action, as UMBC only had one first half turnover and six for the game.
UMBC resumes America East play on Tuesday, Jan. 12, when they play at Boston University.