  A crosscap transposition is an element of the mapping class group of a
nonorientable surface represented by a homeomorphism supported on a one-holed
Klein bottle and swapping two crosscaps. We prove that the mapping class group
of a compact nonorientable surface of genus $g\ge 7$ is generated by conjugates
of one crosscap transposition. In the case when the surface is either closed or
has one boundary component, we give an explicit set of $g+2$ crosscap
transpositions generating the mapping class group.
