A densely inhabited 4 square miles just minutes from downtown Boston, Somerville is already a highly sought after place to live. With the Green Line extension promising to fill in gaps in mbta service, it will become only a hotter place for development.

As Somerville marches forward, however, many current and long-term residents are left reckoning with an uncertain future. The city struggles with how to avoid a fate that is affecting similar urban communities across the nation: the displacement of the very residents who have helped shape their communities into the desirable places they are today. Somerville hopes to buck this trend, looking at ways to leverage large- and small-scale growth to achieve the community’s goals. But can it hold on to the socio-economic, cultural, and ethnic mosaic of the people who live there? Is it possible to provide affordable housing options targeted at a range of income levels?

The city’s political leadership and a smart, engaged citizenry have become partners in envisioning the Somerville of 2030, with a focus on housing affordability as a particularly urgent challenge. The City’s Office of Strategic Planning and Community Development is recrafting its zoning ordinances around the 100 or so comprehensive goals and priorities articulated by the community itself during its three-year-long “SomerVision” process. The values and personality of Somerville permeate the new code, which is designed to address the quality of urban life, in part through several ambitious provisions that will support the construction of inclusionary housing.

Although the zoning overhaul will primarily expand the city’s robust housing affordability efforts for new construction, much of Somerville is already built out. Consequently, a brain trust of community groups, led by the Somerville Community Corporation (SCC), has looked to existing housing stock in established neighborhoods as a source of affordable units. Most of this stock is two- and three-family dwellings, and much of it is being lost to speculation.

Enter Somerville’s 100 Homes Initiative. This entrepreneurial strategy captures existing properties available on the open market, competing for them like a serious buyer, which in this market means acting nimbly and paying with cash. Once acquired, these units are modestly rehabbed and become permanently deed-restricted at various affordability rates. With an initial goal to create 100 new affordable units, the initiative was launched two years ago with enthusiastic backing from the mayor’s office.

The 100 Homes program — funded primarily through subsidies provided under the Community Preservation Act, adopted by Somerville voters in 2012 — preserves not only individual buildings but also a community’s character. With a credit line from the Massachusetts Housing Investment Corporation (an affordable housing lender), the scc can make an offer on a property like a cash buyer.

The program is working. After a two-year pilot phase, five properties have been acquired and a sixth is under agreement, with a yield of 14 new affordable units scattered around the city.

As a result, many current tenants can stay put after the sale of their building rather than face eviction as the property is renovated to capture higher rents or be resold. A model scenario for the program is for scc to buy a property occupied by tenants who qualify for affordable rent. No one would be displaced. An ideal scenario is to purchase an owner-occupied three-family with income-eligible tenants in two units and maintain the owner’s unit at market rate. The result would be a property with a financially sustainable mix of affordable and market-rate units.

With progress to date, the program is now being evaluated and tweaked. 100 Homes delivers units quickly, in contrast to the slow-moving process that encumbers state-funded and federally funded housing initiatives, though the group is still working out how to efficiently and fairly place tenants in the new units. Eventually, scc hopes to transition some units to homeownership as affordable condos.

What is the future of 100 Homes? Given the urgency, the scc is contemplating how to scale up the program. Could a 500 Homes initiative be sustainable? As Somerville continues its building boom and home prices skyrocket, it will become increasingly difficult to acquire and create affordable units for the program. Let’s see what Somerville leadership comes up with next.