We prove a finiteness theorem for the spectral sequence (E-i(del),(d(d
el))(i)) associated to a Riemannian foliation F on a compact manifold
M, and to a flat vector bundle E over M with hat connection del. Using
this result we prove that every Riemannian foliation on a compact man
ifold is tense (in the sense of [F. W. Kamber and Ph. Tondeur, Foliati
ons and metrics, Progr. Math., vol. 32, 1983, pp. 103-152]). We also s
how that the main tautness theorems for Riemannian foliations on compa
ct manifolds, which were proved by several authors, are immediate cons
equences of our results.