In Mexico extension as a professional activity has been revalued, by the Government of the Mexican Republic itself, according to data from SAGARPA there are at least 23 thousand technicians in the registered registry. The segments of attention of producers in Mexico have been defined and new programs are built where inclusion is a common denominator. During two years, a group of 20 specialists from as many institutions met under the auspices of CIMMYT-Mas Agro, to agree on the concept of extensionism and it was possible to elaborate a working document that describes the philosophical, methodological and operative principles of extensionism in Mexico.