A major purpose of this study was to determine whether a selected number of current, commercially prepared spelling series used high frequency words for their word lists. A second purpose was to determine whether students misspelled high frequency words in their writing. Eleven commercially prepared spelling series were selected according to the following criteria: copyright date of 1976 or later, availability at the beginning of the study, and publication in basal format with books for each grade level 2 through 6. Through systematic sampling, 100 words from each grade level of each series were chosen resulting in a total of 5,500 words. Words from students' writing were taken from writing samples by students in grades 3 and 5. "The American Heritage Word Frequency Book" was used to determine word frequency. Results showed that there were significant differences among the spelling series in their number of high frequency words based on a standard measure of word frequency. No one series had the highest number of high frequency words at each grade level. Also, no one series was consistent across grade levels in the number of high frequency words found at each grade level. Although grade 2 should have had the highest number of high frequency words, results showed that grade 3 had the highest number, while grade 4 had the second highest, followed by grades 2, 5, and 6. Finally, the high number of incorrectly samples suggests that students' writing serves as a potential source for spelling words. (HOD)