Psychologists use the thematic apperception test to explore the drives, sentiments, complexes and conflicts of personalities. The TAT is used worldwide in military and industrial settings, for neuropsychological assessment and forensic evaluation, and in creativity and motivation studies. But researchers continue to debate its reliability and validity, and no consensual scoring system or set of norms exists for the TAT. This text retraces the roots of the TAT, along with the circumstances that shaped, and continued to shape, its use. The TAT's history, theoretical and empirical grounding, and continued practical value are explored.