The purpose of this investigation was to identify patterns of spelling errors among first grade children by classifying these errors in terms of their orthographic structure. The children were equally divided into low, middle, and high ability groups according to the number of words in their individual word banks as produced in their written compositions. The classification scheme separated the errors into categories of name and non-name vowels and voiced and unvoiced consonants. Findings in the name vowel categories indicated more errors of omission than substitution across all three ability groups with 80 percent of these errors involving the vowels "a,""e," and "i." However, the non-name vowels included more substitution than omission errors and there were more differences in these types of errors within the three ability groups. Also, the overall percentage of substitutions systematically increased across the ability groups while the overall percentage of omissions systematically decreased. In the consonant categories, consistent types of substitutions appeared within both the voiced and unvoiced categories, with substitutions occurring most frequently among stops and fricatives. (Author/HOD)