This paper reports upon an investigation into skew group rings. The author begins by defining for a pair of unitary rings R,S, \(R\subseteq S\), the term ’right excellent extension’ i.e. S has a normalising basis over R and S is right R-projective. It is shown, for example, that if S is a right excellent extension of R then S is a QF-ring if and only if R is a QF-ring and that R is right hereditary if and only if S is right hereditary. Such results are applied to the study of a skew group ring \(K^*_{\tau}G\) where G is a finite group, K is a field of characteristic \(p>0\), \(\tau:G\to Aut(K)\) is a homomorphism with kernel N, k is the subfield of K fixed elementwise by \(\tau\) (G), P is a p-Sylow subgroup of N and H is the maximal normal subgroup of N of order prime to p. There follow several results on the blocks and centre \(Z(K^*_{\tau}G)\) of \(K^*_{\tau}G\) such as that \(Z(K^*_{\tau}G)\) has a k-basis which is K-free and that the centre Z(K(N)) is an excellent extension of \(Z(K^*_{\tau}G)\). A result of T. Nakayama [Ann. Math., II. Ser. 39, 361-369 (1938; Zbl 0020.34103)] on \(\dim_ kZ(K^*_{\tau}G)\) is also obtained. Certain special classes of skew group rings are characterised. It is shown that \(K^*_{\tau}G\) is primary decomposable if and only if H is p-nilpotent and \(K^*_{\tau}G\) is primary decomposable with at most one non-simple block if and only if N is a p-nilpotent Frobenius group with kernel H and complement P where, extending the usual definition, H and P are allowed to be trivial. The main thrust of this report is in the analysis of \(K^*_{\tau}G\) when N is a p-solvable group of p-length one. Avoiding modular representation theory the author generalises a result of W. Schwarz [J. Algebra 60, 51-75 (1979; Zbl 0418.20003)] and shows that for such a \(K^*_{\tau}G\) and for a projective indecomposable K(N)-module V belonging to a block B with defect group D then \(K-\dim(J^ iV/J^{i+1}V)=K-\dim V.K-\dim(J^ iK(D)/J^{i+1}K(D))\) and that the upper and lower Loewy series for V coincide. The paper concludes by giving a number of equivalent conditions that N be p-solvable with cyclic p-Sylow subgroup such as that \(K^*_{\tau}G\) is of finite representation type and the \(K^*_{\tau}G\)-modules belonging to the same block have the same K-dimension.