Effects of orthographic depth on orthographic learning ability were examined in 10- to 13-year-old children who learnt to read in similar orthographies differing in orthographic depth, defined as consistency of grapheme-to-phoneme correspondences. Danish children who learnt to read a deep orthography underperformed their Swedish counterparts who acquired a shallow orthography on vocabulary, phonological working memory, orthographic learning ability, and a range of first-language (L1: Danish/Swedish) and second-language (L2: English as a foreign language) measures. Orthographic learning ability explained over and above vocabulary and phonological working memory the better performance of Swedish children in comparison with Danish children on L1 reading accuracy and fluency, spelling, and visual word familiarity. With respect to L2 learning, orthographic learning ability determined spelling and visual word familiarity over and above L2 vocabulary and phonological working memory. It is concluded that shallow orthographies promote orthographic learning ability more efficiently than deep orthographies.