Previous authors have noted that there are significant differences bet
ween the provisions of union and nonunion pension plans. I present evi
dence that sheds light on two hypotheses. The first (Parsons, 1983) po
sits that union pensions should encourage earlier retirement because p
roductivity falls as workers age, but union rules prohibit firms from
lowering wages. The second (Freeman, 1985) argues that union pension p
lans reflect the preferences of older more senior workers. I find some
support for both hypotheses.