High industrial development, new consumption habits, and population growth have led to a discussion, in the various sectors of society, about resource scarcity, pollutant emissions, and waste generation. As a result, and in opposition to the linear economic model in which products are eliminated after production and consumption, a new business model emerged, called the “The Circular Economy”. This model is based on reuse, recovery, recycling, and repairing during the design and use cycle of a product. This research intends to make a study of the circular economy in the pulp and paper industries of Portugal and Spain. This sector was chosen because, in addition to representing about 2.5% of Portugal’s industrial production, it has made significant efforts to promote environmentally sustainable development. Therefore, this research intends to present the situation of the pulp and paper sector within the circular economy, making an Iberian comparison between the years 2011 and 2015. This comparison is made through the development of a comparative index based on the results of some environmental indicators. According to the research carried out, the pulp and paper sector in Portugal was about 26% higher in the implementation of the circular economy than the same sector in Spain in 2015, with the peculiarity that this difference has been decreasing in the last five years.