Real estate on Decatur Island is defined by scarcity and scale rather than subdivisions. The island is almost entirely private property, with homes and building sites concentrated in a small number of shared-ownership communities and along the shoreline, while large tracts remain in forest preserve or agricultural use. Many properties are sizable acreage parcels, and community associations hold hundreds of acres of protected forestland in common for hiking and wildlife viewing. Housing ranges from modest island cottages and farmhouses to Northwest-style retreats on waterfront lots. Because there is no ferry and limited infrastructure, buyers tend to be self-sufficient individuals and families seeking privacy, and the market moves slowly, with inventory appearing only occasionally.

Decatur Island does not have a town, but it does have a handful of recognized residential communities and place-names. Decatur Shores and Decatur Northwest are two of the better-known shoreline communities, developed around shared beach access, private docks, and cooperative land ownership. The island's southern tip is held by the San Juan Preservation Trust for conservation and public day-use, while Davis Bay on the east shore provides the island's only public boat ramp. The interior is a mix of farm fields, forest, and private parcels reached by unpaved roads. In practice, the whole island functions as a single close-knit neighborhood, with residents coordinating on everything from road maintenance to the school.

Life on Decatur Island is deliberately simple and self-reliant. With no ferry, no stores, and no municipal services, residents plan around tides and weather, keep boats or planes for travel, and handle much of their own infrastructure. The one-room school is a focal point for island families, and social life revolves around neighbors, shared work, and the occasional community gathering. Groceries, fuel, and supplies arrive by private boat or charter, and errands on Lopez Island, Anacortes, or the mainland require scheduling. It is a lifestyle suited to people who value quiet, autonomy, and connection to the natural world, and who are comfortable with the practical demands of island living.

Decatur Island has a one-room school serving children from kindergarten through eighth grade, a small institution that sits at the center of island family life. Enrollment is tiny, and instruction is necessarily multi-age, with teachers adapting to a handful of students at a time. For high school, families generally arrange schooling off the island, with students commuting by boat or boarding on nearby islands or the mainland. The school is part of the broader San Juan County educational landscape, which includes public districts on the larger ferry-served islands. For island residents, the school is both a practical service and a symbol of the community's determination to keep year-round life viable.

Decatur Island has no Washington State Ferry service, making it one of the San Juans' most secluded inhabited islands. Access is by private boat or by small aircraft using the island's private airstrip. A public boat ramp in Davis Bay on the east side provides a landing point, and freight and vehicles arrive through services such as Island Transporter, while passenger charters including Island Express and Paraclete Charters connect the island to Anacortes and other ports. There are no public paved roads beyond the island's private lanes, and residents generally keep vehicles on both sides of the water. Travel requires planning around weather and daylight, and the nearest ferry terminals are on Lopez and Blakely islands.

Recreation on Decatur Island is quiet and nature-centered. The San Juan Preservation Trust property at the island's southern tip is open for public day-use, offering shoreline walking and wildlife viewing. Residents enjoy beachcombing, kayaking, and boating along the island's coves and anchorages, and the shared forest preserves provide trails for hiking and watching for bald eagles, deer, and marine life. Fishing and crabbing in the surrounding Salish Sea waters are popular, and the island's dark skies and stillness offer a rare level of solitude. For broader recreation, Lopez Island and the other ferry-served San Juan Islands are a short boat trip away, with their parks, trails, and village amenities.