Meta-analyze all published epidemiologic studies reporting pediatric mania or bipolar disorder to investigate whether pediatric bipolar disorder is becoming more prevalent and whether rates vary significantly by country. Searches of PubMed and PsycInfo were conducted through the spring of 2010 using the following search terms: child, pediatric, young, adolescent, epidemiology, prevalence, bipolar, mania, suicide, and psychiatric. We also manually reviewed references in recent reviews of epidemiology of bipolar disorder. All studies reporting rates for mania or hypomania in community epidemiologic samples with participants up to 21 years of age. All articles were coded to extract relevant variables. Prevalence rates were calculated from reported number of cases with bipolar disorders, then logit transformed. Twelve studies were included, enrolling 16,222 youths between the ages of 7 and 21 years during a period from 1985 to 2007. Six samples were from the United States; 6 were from other countries (the Netherlands, the United Kingdom, Spain, Mexico, Ireland, and New Zealand). The overall rate of bipolar disorder was 1.8% (95% CI, 1.1%-3.0%). There was no significant difference in the mean rates between US and non-US studies, but the US studies had a wider range of rates. The highest estimates came from studies that used broad definitions and included bipolar disorder not otherwise specified. Year of enrollment was negatively correlated with prevalence (r = -0.04) and remained nonsignificant when controlling for study methodological differences. Mean rates of bipolar disorder were higher than commonly acknowledged and not significantly different in US compared to non-US samples, nor was there evidence of an increase in rates of bipolar disorder in the community over time. Differences in diagnostic criteria were a main driver of different rates across studies.