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.

Response to Intervention (RTI) models of reading instruction have received much attention in the literature (Fuchs, Mock, Morgan, & Young, 2003; Hosp & Ardoin, 2008; Justice, 2006). Such models call for frequent and high-quality assessment of students' skills. One skill that is vital in the process of learning to read is the ability to sound out letters and blend these sounds together to produce a word. According to Dual Route models of reading (e.g., Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001), these skills comprise the sublexical route to reading. This is best assessed by tests of nonword reading. In this article, 17 tests of nonword reading were reviewed in light of RTI and Dual Route models. The aim of the review was to determine the best available nonword reading tests for use at the Tier One and Tier Two levels of intervention, and the best available nonword reading test for diagnostic (Tier Three) purposes. The review determined that several good-quality tests of nonword reading, suitable for assessing the general functioning of the sublexical route to reading (at the Tier One and Tier Two level), are available, but that no test of nonword reading is available that fulfils all of the desirable criteria for a Tier Three, diagnostic assessment.