The purpose of this study is to report on the development and validation of a game-understanding test procedure in badminton. A basic video-based test was constructed, and primary school children (ages 9–10 and 11–12 years, N = 120) served as participants. An advanced test was designed to detect differences between national level junior badminton players (11–14 years, n = 19) and primary and secondary school children (11–14 years, n = 45). The video-based tests consisted of 15 to 19 different sequences that were simulations of actual offensive and defensive game situations. In every sequence, players were to solve tactical problems by selecting appropriate solutions and arguments for their decisions. Validity and reliability of the tests were examined through these groups, and the findings suggest that the test procedure developed provides a valid and reliable method for assessing game understanding in badminton.