The use of vocabulary assessment scores can help teachers monitor student progress and make pedagogical decisions that promote learning. The purpose of the study was to adapt the interpretation of scores yielded by EVOC, a Spanish vocabulary assessment tool, to measure vocabulary range among 1,662 students between the ages of 6 and 14, based on word frequency bands from a corpus. The methodology included confirmatory factor analysis, the establishment of empirical difficulty indices, and the assemble of the items in terms of the order of appearance of the words in the corpus of school texts. The results show that it is possible to interpret scores in terms of lexical competence development standards, which should provide for better use of data in the teaching and learning of reading and vocabulary.