In the 1940s, several economists in the U.S. Public Health Service devised a cost-saving method known as pooling designs to examine groups of drafted soldiers for disease in a single test. These designs – and the more general problem of testing large populations of items – became known as combinatorial group testing. This lecture will demonstrate the usefulness of group testing with a simple magic trick, describe some modern applications of group testing in genetics, and then illustrate several group testing designs that come from error-correcting codes, which are used to transmit information so that a decoding algorithm can detect and correct errors.