The reading rainbow of young multilingual learners: reading comprehension in the majority (Spanish), regional (Basque) and foreign (English) language

Reading comprehension is crucial in education, serving as the foundation for acquiring knowledge. In multilingual settings, children must develop these skills in multiple languages. However, there is limited understanding of comprehension levels across languages and of the role of influencing factors such as language exposure, non-verbal intelligence (NVI), socioeconomic status (SES), and extramural reading (ER). This study explores how these variables impact the reading comprehension of young learners (aged 10–11) in English (foreign language), Spanish (main language), and Basque (regional language for Basque-immersion participants). The participants were divided into a high-intensity (HI) group (N = 118) and a low-intensity (LI) group (N = 81) within Basque-immersion programs. Results showed correlations among reading comprehension scores in Spanish, English, and Basque. While both groups demonstrated similar Spanish comprehension levels, the HI group excelled in English, particularly among high-NVI learners. LI learners scored lower in Basque compared to Spanish. Regression analyses indicated that NVI and, to a lesser extent, SES influenced reading comprehension across languages. Also, HI learners engaged more in English ER, whereas LI learners favored Basque. However, ER did not have a significant impact on their reading scores. Based on these findings, pedagogical implications for multilingual education contexts will be discussed.