This paper describes three experiments related to differences in discrimination learning. In Experiment 1, sixth-grade subjects were required to judge the situational frequency of items which had occurred from 0 to 4 times on a study list. For one group the study list consisted of high-frequency words. Another group judged low-frequency words which were high in meaningfulness. A third group judged low-frequency words which were low in meaningfulness. A fourth group gave frequency judgments for nonsense items. Items were presented for study and test at a 5-second rate. The results supported the hypothesis that pre-experimental or background frequency differences in materials account for apparent frequency differences. In experiment 2, one group of sixth graders earned a 15-pair verbal discrimination list consisting of low-frequency/high-meaning words. Another group learned pairs of low-frequency/low-meaning words. A third group learned high-frequency words. No significant differences were found. In experiment 3, groups of beginning fourth graders learned high-frequency and low-frequency words presented on a word list. The results indicated that background frequency is negatively related to discrimination learning. (WR)