Let K∕k be a finite galois
extension of number fields, S a finite set of primes of K, and Φ a set of intermediate
fields. We assume that S and Φ are closed under the action of G(K∕k) and that S
contains all the archimedean primes. This paper determines conditions under which
the S-units of fields of Φ “almost generate” those of K (i.e., generate a subgroup of
finite index).