Comprehensive assessments of Paraguay's forest cover (FC) change from the 1970s to the 2000s using Landsat observations were conducted, including a wall-to-wall mapping of changes across the whole country between the 1990s and 2000s, and an assessment of forest area in the Atlantic Forest ecoregion in the 1970s using a systematic sampling approach. The derived wall-to-wall FC change map was evaluated using available high resolution satellite images and aerial photos. The overall accuracy values were 92% or higher in the areas covered by those high resolution data sets. The results revealed that the Atlantic Forest ecoregion experienced the most forest loss, with the 73.4% forest cover in the 1970s decreasing precipitously down to 40.7% by the 1990s and further down to 24.9% by the 2000s. The rapid loss of Atlantic forests was driven by complex social economic forces, including widespread land disputes arising from long time inequalities and profits from exporting agricultural products. Forest changes in the Humid Chaco and the Chaco ecoregions were relatively moderate. However, extensive forests were converted to non-forest land use near a major population center. The results also revealed that so far the established protected areas were effective in protecting forest within their border. However, most of the forests surrounding the protected areas were lost by the 2000s. Loss of Atlantic forest is a major threat to the rich biodiversity found in this region. The alarming deforestation rates over the last three decades and the low percentage of Atlantic forest left by the 2000s call for immediate actions to halt the trends of forest loss.