We study the generalization of the exact solution of two-dimensional Y
ang-Mills theory to the space of all two-dimensional gauge field theor
ies with the symmetry of area-preserving diffeomorphisms. We show that
these theories are exactly solvable when formulated in the space of f
irst-order lagrangians. The equivalence between the space of first-ord
er lagrangians and the space of original lagrangians is interpreted by
the standard renormalization theory.