2262 20160706142649.0 DOI 10.1051/0004-6361/201015829 ASTROimport-419 Groenewegen, M. A. T. 2011 MESS (Mass-loss of Evolved StarS) is a guaranteed time key program that uses the PACS and SPIRE instruments on board the Herschel space observatory to observe a representative sample of evolved stars, that include asymptotic giant branch (AGB) and post-AGB stars, planetary nebulae and red supergiants, as well as luminous blue variables, Wolf-Rayet stars and supernova remnants. In total, of order 150 objects are observed in imaging and about 50 objects in spectroscopy. This paper describes the target selection and target list, and the observing strategy. Key science projects are described, and illustrated using results obtained during Herschel's science demonstration phase. Aperture photometry is given for the 70 AGB and post-AGB stars observed up to October 17, 2010, which constitutes the largest single uniform database of far-IR and sub-mm fluxes for late-type stars. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices and Tables 1 and 2 are only available in electronic form at http://www.aanda.org MESS (Mass-loss of Evolved StarS), a Herschel key program Waelkens, C. Barlow, M. J. Kerschbaum, F. Garcia-Lario, P. Cernicharo, J. Blommaert, J. A. D. L. Bouwman, J. Cohen, M. Cox, N. Decin, L. Exter, K. Gear, W. K. Gomez, H. L. Hargrave, P. C. Henning, T. Hutsemékers, D. Ivison, R. J. Jorissen, A. Krause, O. Ladjal, D. Leeks, S. J. Lim, T. L. Matsuura, M. Nazé, Y. Olofsson, G. Ottensamer, R. Polehampton, E. Posch, T. Rauw, G. Royer, P. Sibthorpe, B. Swinyard, B. M. Ueta, T. Vamvatira-Nakou, C. Vandenbussche, B. van de Steene, G. C. van Eck, S. van Hoof, P. A. M. van Winckel, H. Verdugo, E. Wesson, R. A162 Astronomy and Astrophysics 526 2011 http://esoads.eso.org/abs/2011A%26A...526A.162G published in REFERD