Stellar streams, the tidal remnants of accreted globular clusters and dwarf galaxies, are uniquely powerful tools for studying the Milky Way. In particular, they allow for strong constraints on the local distribution of dark matter, and they provide insight into how our Galaxy has evolved over time. Models of stellar streams enable measurements of the overall shape and mass of the Milky Way’s halo, which is sensitive to dark matter and galaxy formation physics. On smaller scales, stellar streams are one of the most promising methods for detecting the presence of small clumps of dark matter, which will allow for unprecedented constraints on the nature of the dark matter particle. Streams also provide important constraints on the formation of the Milky Way stellar halo and the history of hierarchical structure formation in our Galaxy, as predicted by the standard Lambda Cold Dark Matter (LCDM) cosmological model. These studies require a large, well-observed sample of stellar streams with full 6D position and velocity measurements. Until recently, such a population was unattainable, but with the advent of large surveys, observations of stellar streams have improved significantly in recent years. In this thesis, I present my work on assembling and modeling the first such population of stellar streams in 6D. First, I present the discovery of a large sample of stellar streams in the Dark Energy Survey, which increased the known population of streams by ~50%, as well as the discovery of a unique stellar stream associated with the Palomar 13 globular cluster. I then describe the measurement of the velocities of this new sample of stellar streams via spectroscopic survey and with data from the Gaia satellite, and present results of modeling this population of stellar streams to constrain the distribution of matter in our Galaxy, including the mass of the Milky Way’s largest satellite, the Large Magellanic Cloud. Finally, I conclude and discuss future efforts in the study of near-field cosmology with this population of 6D stellar streams.