Using Current Population Survey data for 1983-93, this article analyzes whether there is a union membership wage premium among full-time, private sector employees covered by union contracts. Ordinary least squares estimates of the membership wage premium are 12%-14%, and allowing membership to be endogenous yields larger estimates. Differences in job tenure, unobservable characteristics, and measurement error cannot fully explain the estimated premium. Significant differences in this premium, as well as in membership rates conditional upon coverage, across various demographic subgroups are also documented. In general, "free riders" do not appear to be free riding. Copyright 2000 by University of Chicago Press.

Workers paid by the piece should be happy to introduce new techniques that increase output, but firms always seem to reduce the piece rate when workers start earning too much money. Workers respond by restricting output and keeping good new ideas to themselves. We show that this outcome is inevitable in a competitive environment. However, there are noncompetitive situations where firms can use piece rates to get cooperation from their workers. These predictions are consistent with case history evidence from the cotton spinning industry in England in the nineteenth century and the Lincoln Electric Company in the United States even today. Copyright 2000 by University of Chicago Press.