Monitoring physical and biological conditions in the open ocean is an inherently difficult task, particularly when monitoring toxic and harmful compounds. Efforts to use biomonitor species to measure and assess ocean and organismal health require considerable information on habitat use and other life history characteristics to contextualize and interpret contaminant data. A large proportion of biomonitoring research focuses on a single species, a single site, and/or a small range (i.e. 1-3) of contaminant classes. While informative, the scope of such studies can limit their applicability, which is concerning as data suggests the abundance of organic and heavy metal contaminants in the ocean is increasing. Contaminants can have sub-lethal effects that affect population viability, and new, unknown contaminants enter the environment with little knowledge of their possible effects and limited ability to monitor these emerging contaminants. Seabirds serve as effective biomonitors for contaminants for multiple reasons. First, seabirds feed at high trophic levels, where toxicants are biomagnified. Because most seabird species are long-lived, birds may bioaccumulate toxicant types into tissues (e.g., fat) over a lifetime, much like humans. Contaminants also accumulate in seabird tissues that can be sampled non-lethally and at low cost, including blood, feathers, and non-viable eggs. Thus, it is also easy to assess the sub-lethal effects of low, but chronic levels of contaminants on a variety of ecological parameters, especially when paired with long-term datasets. Additionally, many seabird tissues have enough volume with which to test for multiple contaminant classes in a single sample. Lastly, seabirds exhibit high breeding site fidelity, so individuals can be sampled and re-sampled with regularity. My research explores how seabirds may be used as biomonitors for a rapidly-changing ocean environment. In Chapter 1, I show that seabird tissues can be used to indicate the magnitude and extent of a wide range of contaminants at the regional scale in the Southern California Bight. In contrast to single species, single site monitoring, regional assessments maximize the ability to use biomonitoring efforts to meet mandated monitoring objectives, prioritize site remediation, and trace the dispersal and uptake of toxicants in marine food webs. The results suggest at least one species, the California least tern (Sterna antillarum browni), may be a robust indicator of contaminant patterns in this region. Chapter 2 investigates blood mercury concentrations as a function of foraging distribution in western gulls (Larus occidentalis) nesting at three colonies off the California and Oregon coast. We found that ocean-foraging gulls had elevated mercury concentrations and also lower fidelity to geographic foraging areas, confirming work that suggests aquatic foragers have greater exposure to methylmercury. As mercury exposure and likely exposure to other contaminants differs across the land-sea gradient, species that forage in marine and terrestrial environments may be used to better understand the ecological consequences of contaminant- associated diet. Chapter 3 uses an established nontargeted approach to examine the presence and patterns of legacy and frequently unmonitored halogenated organic compounds in three albatross species that range the North Pacific. The majority of contaminants we found are currently unmonitored, which demonstrates the extent of chemical contamination beyond urbanized coastal areas to remote coastal regions. We also found support for previous research that suggests differences in broad-scale foraging areas impact contaminant abundance among these three species.