A ring R for which every finitely generated right submodule of S R , the left flat epimorphic hull of R, is projective is termed an extended semi-hereditary ring. It is shown that several of the characterizing properties of Prufer domains may be generalized to give characterizations of extended semi-hereditary rings. A suitable class of PP rings is introduced which in this case serves as a generalization of commutative integral domains. A ring will be said to be a right perfect PP ring if S, the left flat epimorphic hull of R is a regular ring and every cyclic i?-submodule of S R is projective. A ring R will be said to be a right extended semi-hereditary ring if S, the left flat epimorphic hull of R, is regular and every finitely generated right jR-submodule of S R is projective.Clearly every right extended semi-hereditary ring is a right perfect PP ring. In this paper characterizations of both of these classes of rings are given and the ideal structure is discussed. In Section 3 characterizations are given for right extended semi-hereditary rings which are analogous to the "classical" characterizations of Prufer domains.In Hattori (1960) a right .R-module A B was defined to be torsion-free if for all aeA and xeR, ax = 0 implies aeAl^x). Throughout this paper torsion-free will 465 use, available at https://www.cambridge.org/core/terms. https://doi