Introduction -- Section I. Evolution and Diversification: Checklist of New World Marsupials -- Taxonomy and Diversity of Living New World Marsupials -- Cenozoic Metatherian Evolution in the Americas -- Paleogene Metatherians from the Itaboraí Basin: Diversity, Affinities, and Paleobiogegraphic Context.-Postweaning Skull Growth in Living American and Australasian Marsupials: Allometry and Evolution -- Evolutionary Diversification of Skull Morphology in Faunivorous Marsupials: A Comparison between the American and the Australasian Lineages -- Morphology, Form and Function in Didelphid Marsupials -- Hair Microstructure Diversification in Neotropical Marsupials: the Roles of Phylogenetic Signal and Adaptation -- Patterns of Phenotypic Evolution and Diversification in the Short-Tailed Opossum Genus Monodelphis -- Section II. Biogeography: From Bergmann's to Cope's rules: An Overview on the Trait Variation in New World Marsupials -- A Macroevolutionary Approach to Study the Age-Area Relationships for the New World Marsupials -- An Overview of Species Richness and Beta Diversity Patterns of New World Marsupials -- Diversification of the Didelphid Marsupials of South America. -- Diversity and Endemism of Marsupials in the Guiana Region (northeastern Amazonia) -- Diversity, Endemism, and Biogeographical History of Marsupials from the South American "Dry Diagonal" -- Spatial Patterns and Drivers of Species Richness and Endemism of Marsupials in the Atlantic Forest in eastern South America -- Section III. Ecology: Population Dynamics of Neotropical Marsupials -- More than Semelparity or Iteroparity: Diversity of Reproductive Strategies in New World Marsupials -- Movement Patterns, Habitat Selection, and Home Range of New World Marsupials -- Positional Behavior and Locomotor Performance of New World Marsupials: Links with Habitat and Substrate Use -- Food Habits of New World Marsupials -- Feeding Patterns of Marsupials in a Neotropical Savanna: Intra- and Interspecific Diet Variation and Seasonal Patterns -- Activity Patterns of New World Marsupials -- IV. Conservation -- Conservation Biogeography of Living New World marsupials (Didelphimorphia, Microbiotheria, and Paucituberculata). -- Effects of Habitat Loss and Fragmentation on Assemblages, Populations, and Individuals of New World marsupials.-. Effects of Habitat Loss and Fragmentation per se in Didelphid Marsupials of the Atlantic Forest -- Left Out of the Pouch: Marsupials and the Coverage Provided by Protected Areas in Brazil.-. Unraveling Human-Wildlife Interactions in Urban Areas: the Case of Didelphis aurita in a Large Metropolis -- Habitat Loss, Fragmentation, and Transformation are threatening a Relict Marsupial from Southern South American Temperate Rainforests -- Concluding Remarks.