Word recognition skills moderate the effectiveness of reading strategy training in Grade 2

• Aptitude-treatment interaction approach with poor and good readers
• Efficiency of word recognition as moderator for treatment effects
• Poor readers with well-routinized word recognition benefited.
• Strategy training was harmful for poor readers with inefficient word recognition.
• Good readers benefited independently of their word recognition skills.

From a cognitive perspective, efficient word recognition processes are essential for the development of reading comprehension skills in primary school. In contrast, reading interventions are commonly evaluated for struggling readers as a group without assessing the influence of the students' word recognition efficiency. In this study, we followed an aptitude-treatment interaction approach to investigate the extent that the effectiveness of a reading strategy training for second graders with poor (n = 119) and good reading comprehension (n = 116) depends on the students' word reading skills. Compared with children randomly assigned to a control group, only poor readers with routinized word recognition benefited from the intervention, whereas the training was even harmful for poor readers with inefficient word recognition processes. Good comprehenders benefited from the training independently of their word reading efficiency. Hence, reading strategy interventions for poor readers should be implemented in consideration of the students' word recognition skills.