Single top quark production with CMS

We present measurements of single top quark production, performed using CMS data collected in 2010-2011 at a centre-of-mass energy of 7 TeV. The cross section for the electroweak production of single top quarks is measured in the t-channel using various methods. The combined result is used to place a constraint on the CKM matrix element Vtb. The data sample analyzed allows to study also differential distributions. For the first time, we measure single top production in the tW channel.