The Rosetta mission was successfully launched on March 2nd, 2004 for a rendezvous with the short period comet 67P/Churyumov-Gerasimenko in 2014. The new baseline mission foresees also a double fly-by with asteroids 21 Lutetia and 2867 Steins, on the way towards the primary target. This volume collects papers presented at the workshop on "The NEW Rosetta targets. Observations, simulations and instrument performances," held in Capri on October 13-15, 2003. The papers cover the fields of observations of the new Rosetta targets, laboratory experiments and theoretical simulation of cometary processes, and the expected performances of Rosetta experiments. Until real operations around 67/PChuryumov-Gerasimenko will start in 10 years from now, new astronomical observations, laboratory experiments and theoretical models are required. The goals are to increase knowledge about physics and chemistry of comets and to prepare to exploit at best Rosetta data.