We review the problem of fractional statistics as it applies to two cu
rrent areas of interest in condensed-matter physics: the fractional qu
antum Hall effect (FQHE), and high-temperature superconductors (HTSC).
In the case of the former, we emphasize Haldane's recent definition o
f a fractional exclusion principle, and show a relation between this i
dea and the standard definition of fractional statistics in terms of a
complex exchange phase. We show that a fractional exclusion principle
is both appropriate and useful for the quasiparticles in the FQHE. In
the case of the HTSC (Where Haldane's novel definition has not been p
ursued), we review the experimental status of the 'anyon superconducti
vity' model for the HTSC. Here we find much less support for the hypot
hesis that the excitations are anyons. We also argue that the past neg
lect of Haldane's fractional exclusion principle makes the resulting t
heory inconsistent.