Project Summary/Abstract Both language impairments and attention deficits represent relatively common neurodevelopmental disorders. Some reports indicate further that these two commons disorders might frequently co-occur as well. Accounts for why language impairments and attention deficits occur at elevated rates have been largely speculative and limited to data derived from case-control studies, leaving the nature and directions of association unknown. It is also unclear whether co-occurring language impairment and attention deficit represents a different form or separate sub-type of language disorder. The proposed study addresses these gaps by conducting parallel investigations of language growth and behavioral symptom progressions in children with specific language impairment (SLI), attention-deficit/hyperactivity disorder (ADHD), ADHD+SLI, and typical development (TD) over a 4 year period (initial age: 7- 8-years). The specific aims of the project are (1) to determine if there are significant differences between initial groups in their vocabulary, verbal memory, and syntactic growth trajectories. (2): to determine if there are significant differences between groups in their ADHD and executive function symptom progressions. (3): to determine if there are significant group differences in linguistic abilities and behavioral symptoms across full siblings of children with SLI, ADHD, ADHD+SLI, and TD. The project is uniquely positioned to document both risk factors that contribute to the development of new cases of ADHD/SLI over the 7- to 11-year age span as well potential protective factors that contribute to improvements in children's initial symptoms. Important innovations associated with the research strategy include the use of clinical indices that have been vetted for threats of ambiguous symptoms, the collection of sibling data to examine overlapping risks, and the consideration of pharmacological, behavioral, and language intervention effects on individual outcomes. Experimental controls in place to strengthen internal validity and reproducibility include regularly scheduled reliability and fidelity checks, blinded assessments at each time of measurement, and group matching. The research proposed impacts upon several key public health concerns. SLI and ADHD affect millions of student in the U.S. and both have been linked to long-term academic, interpersonal, vocational, and health risk. Thus, from a public health perspective, even small efficiency gains in the identification, differential diagnosis, and integrated management of these two common neurodevelopmental disorders would translate into considerable societal benefit.