There is an increased prevalence of learning disorders (LD) in children with attention-deficit/ hyperactivity disorder (ADHD) as compared to normative rates. Yet little is known about the developmental course or consequences of these co-occurring disorders as affected children reach young adulthood, particularly in females. It is critical to obtain a more complete understanding of the phenotype of co-occurring ADHD/LD in females, as well as to clarify the differential impact of reading and math disorders on outcomes in girls with ADHD. The goals of this study were to understand the differential and interactive effects of childhood ADHD and LD in females on key academic, behavioral, emotional, and social outcomes in young adulthood and to examine the course, developmental changes, and outcomes associated with persistence versus remittance of these disorders. The study has three main aims: (1) to determine whether girls with childhood-defined ADHD + LD have more significant negative outcomes in young adulthood than girls with ADHD only, LD only, or comparison girls, (2) to investigate the course of ADHD and LD in girls who were diagnosed with either or both disorders as children, and (3) to examine functional outcomes in those whose ADHD and/or LD symptoms persist versus those whose symptoms remit. The present study utilizes data from a longitudinal study of girls with and without ADHD, the largest known sample of childhood-diagnosed girls with ADHD and ethnicity matched comparison girls. Data were first collected at baseline (Wave 1), when the girls were 6-12 years old. Overall, the results indicate that childhood ADHD symptoms have the most significant implications for a variety of negative social, emotional, behavior, and academic young adult functional outcomes. Childhood learning disorders have some specific predictive value for young adult outcomes: childhood reading disorder (RD) status predicted likelihood of suicide attempt at young adulthood and childhood mathematics disorder (MD) status predicted social functioning at the young adult follow-up. Girls with childhood ADHD + RD and ADHD + MD demonstrated similar functioning in young adulthood to those girls who had a childhood diagnosis of ADHD alone. At follow-up, young adult ADHD status again predicted a wide range of negative functional outcomes, while young adult RD diagnosis specifically predicted concurrent internalizing disorders, frequency of self-harm behavior, and school problems. ADHD and RD diagnoses showed interactive effects for social functioning and school problems; simple main effects analysis revealed that ADHD and RD diagnoses were predictive of poorer outcomes in the absence of the other disorder. MD diagnosis at young adulthood was predictive of poor social functioning and school problems. Most girls with ADHD and a concurrent learning disorder lost one or both diagnoses by young adulthood, and the course of ADHD did not appear to be affected by the presence of an LD at baseline or persistence vs. remittance of an LD into adulthood. Remittance of symptoms from childhood to young adulthood influenced functional outcomes. Remittance of ADHD by young adult follow-up was associated with improvements in self-esteem, psychopathology, frequency of self-harm behavior, and school problems. With remittance of MD by young adulthood, there was a reduction in suicide attempts. The results indicate that childhood ADHD symptoms have significant implications for a variety of negative social, emotional, behavior, and academic functional outcomes, but childhood learning disorders have more limited predictive value for young adult outcomes. Moreover, remission of ADHD symptoms was linked to better functional outcomes across a range of emotional, behavioral, and academic measures, emphasizing the importance of targeting early symptoms and related impairments.