Headache can affect all aspects of a child's functioning, leading to negative affective states (eg, anxiety, depression, anger) and increased psychosocial problems (for instance, school absences, problematic social interactions). For children and adolescents who experience frequent headache problems, comorbid psychological issues are a well-recognized, but poorly understood, clinical phenomenon. The confusion surrounding the relationship between pediatric headache and psychopathology exists for several reasons. First, in some cases, headache has been inappropriately attributed to psychological or personality features based on anecdotal observations or interpretations that go beyond the available data. Additionally, measures of psychopathology have not always adhered to the American Psychiatric Association's diagnostic criteria, thus reducing the reliability of diagnostic judgments. Furthermore, the diagnosis of headache has not always followed standard criteria, and has been complicated by the emergence of new terms and evolving measures. Finally, methodological shortcomings, such as incomplete descriptions of the procedures and criteria used for the study, inadequate descriptions of headache severity, lack of a control group for comparison with individuals without headaches, reliance primarily on cross-sectional research designs that are often discussed with inferences to causal hypotheses, and the use of unstandardized assessment measures, have significantly limited the validity of research findings. The goal of the current review is to examine the extant literature to provide the most up-to-date picture on what the research has made available about the magnitude, specificity, and causes of psychopathology in children and adolescents with headache, in an effort to further elucidate their relationship and prompt a more methodologically rigorous study of these issues.