Determining word meanings that ought to be taught or introduced is important for educators. A sequence for vocabulary growth can be inferred from many sources, including testing children's knowledge of word meanings at various ages, predicting from print frequency, or adult-recalled Age of Acquisition. A new approach, Word Maturity, is based on applying Latent Semantic Analysis to patterns of word occurrences in texts used with children. This article reports substantial correlations in the 0.67 to 0.74 range between Word Maturity estimates and the ages of acquiring word meanings from two studies of children's knowledge of word meanings, controlling for homographs. The agreement among these markedly different methods for determining when word meanings are understood opens up new research avenues. In addition, we have found that print frequency is associated with Word Maturity and tested knowledge of word meanings and that understanding concrete meanings required less print frequency exposure than verbally defined meanings.