This paper develops two models of the lobbying of interest groups to examin
e the effect of the number and size of interest groups on rent dissipation.
In cases where individuals ignore the effect of the lobbying activities on
the rent size, the number of groups is negatively related to rent dissipat
ion and there exists an inverse relation between the extent of egalitariani
sm of within-group rent sharing rules and the total rent dissipation in the
symmetric setting. Model two examines the case where each individual in ea
ch group takes into account the effect of lobbying activities on the total
"pie", of which she/he competes for a share through within-group and betwee
n-group interaction. The relation between the number of symmetric groups an
d the total rent dissipation is shown to be an inverted "U"-shape, contrary
to the conventional wisdom that holds a monotonous relation between the tw
o variables.