The effect of quantum corrections to a conformally invariantfield theory for a self-interacting scalar field on a curvedmanifold with boundary is considered. The analysis is mosteasily performed in a space of constant curvature the boundaryof which is characterized by constant extrinsic curvature. Anextension of the spherical formulation in the presence of aboundary is attained through use of the method of images.Contrary to the consolidated vanishing effect in maximallysymmetric spacetimes the contribution of the massless `tadpole'diagram no longer vanishes in dimensional regularization. As aresult, conformal invariance is broken due to boundary-relatedvacuum contributions. The evaluation of 1-loop contributions tothe two-point function suggests an extension, in the presence ofmatter couplings, of the simultaneous volume and boundaryrenormalization in the effective action.