  The Schur Theorem says that if $G$ is a group whose center $Z(G)$ has finite
index $n$, then the order of the derived group $G'$ is finite and bounded by a
number depending only on $n$. In the present paper we show that if $G$ is a
finite group such that $G/Z(G)$ has rank $r$, then the rank of $G'$ is
$r$-bounded. We also show that a similar result holds for a large class of
infinite groups.
