Abstract We present a selection of the first physics results from the CMS experiment in proton-proton collisions, based on data collected at various beam energies during December 2009 and 2010. The measurements include particle production in the soft-QCD regime as well as high- p T spectra and correlations. Inclusive jet production and b-jet production have been studied down to p T below 20 GeV/ c , exploiting a novel technique based on the full reconstruction of the event (“particle flow”). Studies of heavy-flavour (open charm and beauty) production have profited from the excellent vertexing performance of the detector, which enables a precise reconstruction of the associated secondary vertices. This capability has also been used to measure the production of J/ ψ mesons promptly produced, independently from those coming from the decay of b hadrons. The production cross sections of the J/ ψ and ϒ states, in pp collisions at 7 TeV, have been measured in several rapidity intervals and down to very low p T .