A congruency theorem is proven far an ordered pair of groups of homeom
orphisms of a metric space satisfying an abstract dilation-translation
relationship. A corollary is the existence of wavelet sets, and hence
of single-function wavelets, for arbitrary expansive matrix dilations
on L-2(R-n). Moreover for any expansive matrix dilation, it is proven
that there are sufficiently many wavelet sets to generate the Borel s
tructure of R-n.