55 Response to phonics through spelling intervention 3 Introduction Reading and spelling are essential skills in life and contribute to quality of life (Stein et al., 2011). It is thus crucial that all children reach sufficient reading and spelling levels. However, learning to read and spell is not an easy task for all children. To become a proficient reader and speller, an efficient recurrent network of phonological, orthographic, and semantic representations needs to be built (Seidenberg & McClelland, 1989). Previous research has consistently pointed out that bi-directional relationships between phonology and orthography are crucial for the development of both reading and spelling abilities (Bosman & Van Orden, 1997). Children with dyslexia have severe problems in building up these phonology–orthography connections (Lyon et al., 2003), although phonics interventions have been relatively successful in strengthening the connections (for a review, see Galuschka et al., 2014). It is important to note that such interventions have mainly focused on reading (i.e., going from orthography to phonology) rather than reading and spelling combined (i.e., going fromphonology to orthography as well, but see Galuschka et al., 2014 and Johnston & Watson, 2006). The effectiveness of a so-called phonics through spelling intervention, aiming to enhance the bi-directional relationships between phonology and orthography, has not yet been demonstrated. In the current study, we therefore examined whether a phonics through spelling intervention benefits both reading and spelling in children with dyslexia and whether such effects are consistent across cognitive profiles. Problems in learning to read and spell for children with dyslexia When learning to read, children learn the principle of phonological recoding, that is, to decode words by sounding out graphemes and blending these sounds into words (Castles et al., 2018). With extensive practice, the orthographic and phonological representations and connections between the two get stored in memory. In learning to spell words, the reversed process (i.e., orthographic recoding) occurs. Both phonological and orthographic recoding processes build upon the bi-directional connection between phonological and orthographic representations (Bosman & Van Orden, 1997). The strength of the bi-directional relationship and the specificity of bothphonological and orthographic representations differ among children (Perfetti & Hart, 2002), with words with high-quality representations being read and spelled better than words with lower lexical quality (Perfetti, 2007; Perfetti et al., 2005). Children develop reading and spelling problems when the bi-directional relations between phonological and orthographic representations are less strong (Melby-Lervåg et al., 2012; Wimmer &Mayringer, 2002). This is especially the case for children with dyslexia. These children have missing, inaccurate, or underspecified representations caused by a phonological deficit (Conrad, 2008). As a consequence, these children have large difficulties to read words and pseudowords both accurately and fluently and spell words correctly (Lyon et al., 2003).