Larval and juvenile lumpfish, Cyclopterus lumpus L., were collected and measured over a 20-year period, 1979–1999, from tidepools along the coast of Maine. Using this extensive data base reduces the effects of annual variations in hatching times, early growth patterns, and locale for analyzing monthly size using length measurements. This can provide an effective field measurement of intertidal growth. Most fish were encountered during the months of July and August, and even when adjusted for number of sampling trips, 78% of the juveniles were encountered in tidepools during these months. Based on average lengths, size increased by 23% between June and July, 43% between July and August, and 34% between August and September.