  Orbital period changes of binary stars may be caused by the presence of a
third massive body in the system. Here we have searched the archive of the Wide
Angle Search for Planets (SuperWASP) project for evidence of period variations
in 13927 eclipsing binary candidates. Sinusoidal period changes, strongly
suggestive of third bodies, were detected in 2% of cases; however, linear
period changes were observed in a further 22% of systems. We argue on
distributional grounds that the majority of these apparently linear changes are
likely to reflect longer-term sinusoidal period variations caused by third
bodies, and thus estimate a higher-order multiplicity fraction of 24% for
SuperWASP binaries, in good agreement with other recent figures for the
fraction of triple systems amongst binary stars in general.
