Developmental dyslexia and specific language impairment (SLI) are often considered distinct disorders, but recent research suggests they may represent different manifestations of the same underlying issue, differing in severity or developmental stage. The authors argue that focusing solely on phonological processing in dyslexia overlooks the significant roles of semantic and syntactic deficits in SLI, which affect reading comprehension and fluent reading in adolescence. They propose a two-dimensional model to capture the phenotypic features of these disorders, highlighting that they occupy different areas of a multidimensional space. SLI affects 3-10% of children, characterized by oral language lag without apparent reasons, while dyslexia is identified by poor literacy skills despite adequate intelligence. Both disorders require adequate hearing and no major handicapping conditions. Historically, research on these disorders followed separate paths, but recent studies suggest they may lie on a continuum rather than being distinct. The authors argue that while there are behavioral similarities, it is helpful to retain a distinction between literacy difficulties and broader spoken language issues. Dyslexia is often linked to phonological processing deficits, but studies show that semantic and syntactic issues also affect literacy. Some children with SLI may have phonological and non-phonological language impairments affecting reading. The authors propose a two-dimensional model where dyslexia and SLI occupy different areas, with continuities but differences in subtypes. They emphasize the need for more than two dimensions to fully capture the range of difficulties. The authors also discuss the importance of distinguishing between proximal and distal causes of disorders, noting that early auditory deficits can have long-term effects on phonological representations. Neurobiological and etiological factors are considered, with environmental influences playing a role. The authors argue that while there are similarities between SLI and dyslexia, they are not the same disorder, and a two-dimensional model is needed to capture their differences. Diagnostic issues are highlighted, with a focus on the role of IQ discrepancy in defining these disorders. The authors suggest that IQ discrepancy criteria may not be reliable, and alternative approaches, such as cognitive marker approaches, may be more effective. They argue that a single dimension of impairment, such as phonological deficit, is insufficient to capture the complexity of these disorders. The authors conclude that while there are similarities between SLI and dyslexia, they are not the same disorder, and a two-dimensional model is needed to capture their differences. They emphasize the importance of considering both cognitive and neurobiological factors in understanding these disorders.Developmental dyslexia and specific language impairment (SLI) are often considered distinct disorders, but recent research suggests they may represent different manifestations of the same underlying issue, differing in severity or developmental stage. The authors argue that focusing solely on phonological processing in dyslexia overlooks the significant roles of semantic and syntactic deficits in SLI, which affect reading comprehension and fluent reading in adolescence. They propose a two-dimensional model to capture the phenotypic features of these disorders, highlighting that they occupy different areas of a multidimensional space. SLI affects 3-10% of children, characterized by oral language lag without apparent reasons, while dyslexia is identified by poor literacy skills despite adequate intelligence. Both disorders require adequate hearing and no major handicapping conditions. Historically, research on these disorders followed separate paths, but recent studies suggest they may lie on a continuum rather than being distinct. The authors argue that while there are behavioral similarities, it is helpful to retain a distinction between literacy difficulties and broader spoken language issues. Dyslexia is often linked to phonological processing deficits, but studies show that semantic and syntactic issues also affect literacy. Some children with SLI may have phonological and non-phonological language impairments affecting reading. The authors propose a two-dimensional model where dyslexia and SLI occupy different areas, with continuities but differences in subtypes. They emphasize the need for more than two dimensions to fully capture the range of difficulties. The authors also discuss the importance of distinguishing between proximal and distal causes of disorders, noting that early auditory deficits can have long-term effects on phonological representations. Neurobiological and etiological factors are considered, with environmental influences playing a role. The authors argue that while there are similarities between SLI and dyslexia, they are not the same disorder, and a two-dimensional model is needed to capture their differences. Diagnostic issues are highlighted, with a focus on the role of IQ discrepancy in defining these disorders. The authors suggest that IQ discrepancy criteria may not be reliable, and alternative approaches, such as cognitive marker approaches, may be more effective. They argue that a single dimension of impairment, such as phonological deficit, is insufficient to capture the complexity of these disorders. The authors conclude that while there are similarities between SLI and dyslexia, they are not the same disorder, and a two-dimensional model is needed to capture their differences. They emphasize the importance of considering both cognitive and neurobiological factors in understanding these disorders.