German works councils are often thought of as operating in all firms that exceed the basic size threshold (of five permanent employees) established under law. Drawing on a new large-scale, representative German data set, we report that only one-fifth of firms in our sample have works councils even if such firms do account for almost three-fourths of employment. The principal factors behind works council presence emerge as fairly conventional: firm size, firm age, branch plant status, the gender composition of the work force, and certain working arrangements. There are also signs of a close relation between workplace union density and council presence. However, some controversial causal links suggested in an earlier econometric literature receive little support.