This study investigated the potential of pre-learning frequently occurring low-frequency vocabulary as a means to increase comprehension of television and incidental vocabulary learning through watching television. Eight television programmes, each representing different television genres, were analysed using the RANGE program to determine the 10 most frequent low-frequency word-families in each programme and the coverage that they represented. The results showed that coverage of the 10 most frequent low-frequency word-families ranged from 0.70% to 3.91%, coverage of the most frequent 3,000 to 3,999 word-families ranged from 0.22% to 2.58%, and coverage of the 4,000 to 4,999 word-families ranged from 0.35% to 1.96%. This result shows the relative value of pre-learning vocabulary in television programmes and provides a strong argument for pre-learning vocabulary. The findings also suggested that if learners knew the most frequent 3,000 word-families and pre-learned low-frequency vocabulary, comprehension and incidental vocabulary learning may increase. (Contains 5 tables.)