  In this paper we discuss gauging one-form symmetries in two-dimensional
theories. The existence of a global one-form symmetry in two dimensions
typically signals a violation of cluster decomposition -- an issue resolved by
the observation that such theories decompose into disjoint unions, a result
that has been applied to, for example, Gromov-Witten theory and gauged linear
sigma model phases. In this paper we describe how gauging one-form symmetries
in two-dimensional theories can be used to select particular elements of that
disjoint union, effectively undoing decomposition. We examine such gaugings
explicitly in examples involving orbifolds, nonsupersymmetric pure Yang-Mills
theories, and supersymmetric gauge theories in two dimensions. Along the way,
we learn explicit concrete details of the topological configurations that path
integrals sum over when gauging a one-form symmetry, and we also uncover
`hidden' one-form symmetries.
