Sandy beach ecosystems provide vital foraging habitat for invertebrates, birds and surfzone fishes. They are also among the most intensely used coastal ecosystems for human recreation, providing support for coastal economies. Our limited knowledge of the fundamental ecology of sandy beaches has been an impediment to basic conservation planning and natural resource management of these important ecosystems. Recently completed ecosystem surveys of sandy beaches in Northern California provide new insights. Over 73 bird species and 135 invertebrate species were observed across 22 sandy beaches. These ecosystems, which occupy about 40% of the shoreline habitat in the region, are fueled by spatial subsidies of drift macrophytes and surfzone phytoplankton, linking their ecology to the production and proximity of adjacent marine ecosystems. Smaller pocket beaches common to this region had strikingly different community structure from longer sandy beaches. Ecosystem functions and services of sandy beaches are threatened by the “coastal squeeze” between development and sea level rise, and by some management practices focused on supporting economically important recreation or infrastructure without sufficient consideration of ecological impacts. These new findings provide increased ecological knowledge of sandy beaches to support coastal zone planning and management, and is one of the beneficial outcomes of baseline ecosystem monitoring done to support California’s network of marine protected areas.