L3C is a Low-profit Limited Liability Company, a for-profit business model that supports financing for socially beneficial enterprises that produce margins below those of a normal market-driven investment. This "third sector" hybrid supports self-sustaining social ventures such as affordable housing, Brownfield redevelopment, urban agriculture and other sustainable development initiatives.

L3Cs bring together a mix of foundations, trusts, endowments, pension plans, individuals, corporations, and governmental entities to achieve social objectives while operating according to for-profit metrics. Its particular niche relates to IRS regulations for Program Related Investments (PRIs) which foundations can make using all or part of their required 5% annual payout. PRIs have been unfavorable for foundations in the past due to expensive "private letter rulings" ensuring the public benefit of their investment. The L3C streamlines the PRI process, leveraging non-profit capital to attract private investment.