This article shares the results of the investigation on environmental sustainability practices within public libraries in Portugal for the Master Course in Library and Information Science at Lisbon University.

The work intends to be a line of thought that meets the goals for sustainable development outlined by the United Nations and the International Federation of Libraries Association – a proposal for the inclusion of libraries and information in the post-2015 agenda.

The research of green libraries around the world demonstrated a growing number that applies environmental sustainability criteria in their strategic and management action.

Are emerging academic research, conferences and seminars devoted to the theme, proposals for revision of the academic curriculum in Library Information Science. Library professional associations worldwide are creating working groups and encourage debate on environmental sustainability and the concept of "global library".

To understand the Portuguese situation in this matter, questionnaires were sent to all municipal libraries in each district, resulting in a sample of 84 public libraries.