This study investigated the growth of word-decoding skills throughout the elementary school years for a representative sample of 2,819 Dutch children. Children's decoding abilities for (a) regular consonant-vowel-consonant words, (b) complex monosyllabic words with consonant clusters in prevocalic and postvocalic position, and (c) polysyllabic words were assessed on two occasions in each school year (Grades 1-6). The growth of word-decoding skills was found to be largely a matter of increased speed. Growth curve analyses showed a gradual curvilinear model to be superior to a step-model for all word-decoding skills. Furthermore, the three measures of word decoding define a common factor and show strong longitudinal stability. Some unique variance for the three word-decoding skills also emerged suggesting that the development of fully proficient word-decoding skills requires the learning of orthographic complexities. (Contains 4 figures and 5 tables.)