Habitat loss is one of the main threats to global biodiversity and ecosystem services. Human development, resource extraction, and climate change all contribute to the degradation or loss of ecosystems worldwide and in California. To counter these impacts, development may be regulated by following a general mitigation hierarchy where the priority is to first avoid injury to natural resources, then minimize remaining impacts, and finally, compensate for any unavoidable losses. This last step, known as compensatory mitigation, can offset environmental impacts through the restoration, enhancement, preservation, or creation (i.e., establishment) of habitat. My research focuses on three aspects of this process: the quantification of impacts to habitat, the cumulative effects of the permitted development, and strategies to improve outcomes of restoration projects. In Chapter 1, I review the cumulative impacts of development permitted by the California Coastal Commission between 2010 and 2018. Wetland habitat was the most frequently impacted, and mitigation usually took the form of restoration and was predominantly on-site and in-kind. I also provide recommendations for improving the compensatory mitigation process. In Chapter 2, I review metrics and tools that quantify impacts to seagrasses, kelps, and other macroalgae. I provide a list and chart to identify tools and applications best suited for ecological valuation and equivalency analysis for mitigation. In Chapter 3, I demonstrate restoration actions that can establish cover and survivorship of a dominant species at a restored tidal marsh in central California. Irrigation and larger plants provided the most cost-effective strategies in the short-term, when compensatory mitigation projects are likely to be held to performance standards. The topics of this thesis are varied but all relate back to the process of compensatory mitigation, the goal of which is to ensure the persistence of natural resources for present and future generations.