This study investigated children's sensitivity to spelling consistency, and lexical and sublexical (rime) frequency, and their use of explicitly learned canonical vowel graphemes in the early stages of learning to spell. Vowel spellings produced by 78 British children at the end of reception year (mean age 5 years, 7 months) and 6 months later in mid-Year 1 were assessed. Regression analyses revealed that, at both test times, knowledge of sound-letter correspondences influenced spelling performance; however, unconditional consistency of vowel spellings affected children's spelling most strongly, over and above additional effects of word and rime frequency and the complexity of the target vowel grapheme. The effect of conditional consistency of vowel spellings given coda contexts was not significant. Thus, young children are sensitive to various statistical properties of the orthography from the earliest phases of spelling development and, in particular, to the unconditional consistency of the vowel spelling pattern.