Tinley Park, village, Cook and Will counties, northeastern Illinois, a residential suburb of Chicago; incorporated 1892. A state mental health center and World Music Theatre, a large outdoor theater, are here. The community, settled by Germans before 1860, is named for the Tinley brothers, prominent railroad officials. It formerly was called New Bremen. Population 26,171 (1980); 37,121 (1990); 48,401 (2000).