This volume contains the proceedings of the LATIN 2000 International Conference (LatinAmerican Theoretical INformatics), to be held in Punta del Este, Uruguay, April 10-14, 2000. This is the fourth event in the series following Sao Paulo, Brazil (1992), Valparaiso, Chile (1995), and Campinas, Brazil (1998). LATIN has established itself as a fully refereed conference for theoretical computer science research in Latin America. It has also strengthened the ties between local and international scientific communities. We believe that this volume reflects the breadth and depth of this interaction....