This design project for affordable housing for New York City’s small lots proposes a model of CO-LIVING based on optimization, flexibility and sustainability of housing. Over the last years the city’s population has peaked, on one hand leading to the growth of its economical power but, on the other, to problems related to elevated population density, insufficient affordable housing production, and higher gap between rents and incomes. Therefore, in a pricey real estate market like New York City’s, co-living constitutes a new and adaptive way to share housing expenses and therefore reducing living costs. Moreover, the concept of co-living, that promotes sharing of living spaces and common facilities, provides for a sense of community that often lacks in large cities.