The focus of this paper is on the assessment of the two main processes that children must acquire at the single word reading level: word recognition (lexical) and decoding (nonlexical) skills. Guided by the framework of the dual route model, this study aimed to (1) investigate the impact of item characteristics on test performance, and (2) determine to what extent widely used reading measures vary in their detection of lexical and nonlexical reading difficulties. Thirty children with reading difficulties were administered selected reading subtests from the Woodcock-Johnson III, the Wechsler Individual Achievement Test - Second Edition, the Castles and Coltheart Reading Test 2(CC2), as well as a measure of nonverbal IQ. Both within-subjects analyses and descriptive data are presented. Results suggest that in comparison to a pure measure of irregular word reading, children with reading difficulties perform better on word identification subtests containing both regular and irregular word items. Furthermore, certain characteristics (e.g., length, similarity to real words) appear to influence the level of difficulty of nonword items and tests. The CC2 subscales identified the largest proportions of children with reading difficulties. Differences between all test scores were of statistical and clinical significance. Clinical and theoretical implications are discussed.