This paper presents a discussion regarding Public Health's main challenges: knowledge of it, professional practice and training human resources. It begins by recognising Latin-America's unequal and polar socio-sanitary context and the sanitary field's myriad single referents, paying special attention to essential public health functions, the Millennium development goals and the Latin-American Association of Public Health Education. Emphasis is placed on three components: knowledge of public health (levels, domains, disciplines, temporality, dimensions and complexity), social practice (state-public, collective general practice and group professional practice) and human resources' training (professional, technical, training and up-dating). An essential challenge is then identified for each of these components and a set of proposals to be launched from the Latin-American Association of Public Health Education is outlined (interchange, partnerships and advocacy).