This is an announcement for the paper "Rosenthal's theorem for subspaces of noncommutative Lp" by Marius Junge and Javier Parcet. Abstract: We show that a reflexive subspace of the predual of a von Neumann algebra embeds into a noncommutative Lp space for some p>1. This is a noncommutative version of Rosenthal's result for commutative Lp spaces. Similarly for 1 < q < 2, an infinite dimensional subspace X of a noncommutative Lq space either contains lq or embeds in Lp for some q < p < 2. The novelty in the noncommutative setting is a double sided change of density. Archive classification: Functional Analysis; Operator Algebras Remarks: 34 pages The source file(s), Rosenthal.tex: 103990 bytes, is(are) stored in gzipped form as 0604510.gz with size 30kb. The corresponding postcript file has gzipped size 144kb. Submitted from: jparcet@crm.es The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/math.FA/0604510 or http://arXiv.org/abs/math.FA/0604510 or by email in unzipped form by transmitting an empty message with subject line uget 0604510 or in gzipped form by using subject line get 0604510 to: math@arXiv.org.