  We study the scaling behaviour of dispersion potentials and forces under very
general conditions. We prove that a rescaling of an arbitrary geometric
arrangement by a factor a changes the atom-atom and atom-body potentials in the
long-distance limit by factors 1/a^7 and 1/a^4, respectively and the Casimir
force per unit area by 1/a^4. In the short-distance regime, electric and
magnetic bodies lead to different scaling behaviours. As applications, we
present scaling functions for two atom-body potentials and display the
equipotential lines of a plate-assisted two-atom potential.
