Abstract. This paper is based on the seemingly new observation that the Schur multiplier M (G) of a d-generator group of prime-power order p n has order |M (G)| ≤ p d(2n−d−1)/2 . We prove several related results, including sufficient conditions for a sharper bound on |M (G)| to be an equality.Let G be a group with centre Z. Schur [13] observed that the commutator subgroup [G, G] is finite whenever the quotient G/Z is finite. Wiegold [17] obtained an estimate for the order of [G, G] in terms of the order of G/Z; in particular he showed that if G/Z has prime-power order p n , then the order of [G, G] is at most p n(n−1)/2 . This bound can be attained for all n ≥ 1, but only if G/Z is elementary abelian. As a corollary, Wiegold re-derived Green's bound [7] on the order of the Schur multiplier of a prime-power group. Gaschütz, Neubüser and Yen In this article we reduce the above bounds on [G, G] by incorporating, in turn: (1) the number of generators of G/Z; (2) the abelian group structure of the quotients of the lower central series of G/Z; (3) the restricted Lie algebra structure of the quotients of the lower p-central series of G/Z; (4) the "breadth in G" of the preimages of the generators of G/Z. The fourth approach (which is the only one to involve more than the structure of G/Z) complements a result of Vaughan-Lee [16]. We obtain corresponding reductions in the above-mentioned bounds on the Schur multiplier. As an application we obtain a rough upper bound on the number of d-generator groups of order p n . Furthermore, our results are presented in such a way as to yield bounds on the Frattini subgroup of a prime-power group.Let p be any prime, and let q ≥ 0 be any nonnegative integer multiple of p. (We are interested mainly in the cases q = 0 and q = p.) Given a group G we let Z q (G) denote the subgroup of the centre of G consisting of those elements with order dividing q. Given a normal subgroup N in G, we let N# q G denote the subgroup of G generated by the commutators ngn −1 g −1 and powers n q for n ∈ N , g ∈ G.