Childhood tuberculosis accounts for a significant proportion of the global tuberculosis disease burden. However, tuberculosis in children is difficult to diagnose, because disease tends to be paucibacillary and sputum samples are often not easy to obtain. The diagnosis of tuberculosis in children is traditionally based on chest radiography, tuberculin skin testing, and mycobacterial staining/culture from appropriate samples. Newer diagnostic strategies have included improved bacteriologic and molecular methods, as well as new methods for sample collection from children. Recently, immune-based diagnostics, such as the interferon-gamma release assays, have been introduced for clinical use. These tests do not offer substantial improvements in sensitivity over tuberculin skin testing for the diagnosis of active disease but may be useful in excluding false-positive tuberculin skin tests. Further research is needed to develop better diagnostic tests for tuberculosis in children.