Recently, interest in nonlinear dynamics in economics and other scienc
es has grown rapidly. Mode-locking is a typical phenomenon that can oc
cur in systems where several oscillatory processes interact. For linea
r systems, the principle of superposition applies. However, as soon as
nonlinear interactions become significant, this principle ceases to b
e valid, and two or more oscillatory modes will tend to adjust to one
another to produce a ''locked'' solution in which one mode performs pr
ecisely q cycles each time the other mode performs p cycles, with p an
d q being integers. In this study we discuss mode-locking in the conte
xt of the well-known Goodwin business cycle. We demonstrate how a simp
le model of this cycle when perturbed by a sine wave can produce mode-
locking along with the associated phenomena of a devil's staircase and
so-called Arnol'd tongues. (C) 1997 Elsevier Science Inc.