Abstract. The Jiang-Su algebra Z has come to prominence in the classification program for nuclear C * -algebras of late, due primarily to the fact that Elliott's classification conjecture in its strongest form predicts that all simple, separable, and nuclear C * -algebras with unperforated K-theory will absorb Z tensorially, i.e., will be Z-stable. There exist counterexamples which suggest that the conjecture will only hold for simple, nuclear, separable and Z-stable C * -algebras. We prove that virtually all classes of nuclear C * -algebras for which the Elliott conjecture has been confirmed so far consist of Z-stable C * -algebras. This follows in large part from the following result, also proved herein: separable and approximately divisible C * -algebras are Z-stable.