The limited liability limited partnership (LLLP) is a relatively new modification of the limited partnership, a form of business entity recognized under U.S. commercial law. An LLLP is a limited partnership and as such consists of one or more general partners and one or more limited partners. The general partners manage the LLLP, while typically the limited partners only have a financial interest.

The difference between an LLLP and a traditional LP is with respect to the general partner's liability for the debts and obligations of the limited partnership. In a traditional limited partnership the general partners are jointly and severally liable for the debts and obligations of the limited partnership; limited partners are not liable for those debts and obligations beyond the amount of their respective capital contributions.

In an LLLP, by having the limited partnership make an election under state law, the general partners are afforded limited liability for the debts and obligations of the limited partnership that arise during the period that the LLLP election is in place. Certain LLLP elections take the form of the limited partnership electing to be a limited liability partnership (this is the format used in, for example, Delaware) while in other states the election is made in the certificate of limited partnership (examples being Florida, Hawaii and Kentucky). Most states require that an LLLP identify itself in its name, but those requirements are not universal.

A limited partnership is a form of partnership similar to a general partnership, except that in addition to one or more general partners (GPs), there are one or more limited partners (LPs). It is a partnership in which only one partner is required to be a general partner.

The GPs are, in all major respects, in the same legal position as partners in a conventional firm, i.e. they have management control, share the right to use partnership property, share the profits of the firm in predefined proportions, and have joint and several liability for the debts of the partnership.

As in a general partnership, the GPs have actual authority as agents of the firm to bind all the other partners in contracts with third parties that are in the ordinary course of the partnership's business. As with a general partnership, "An act of a general partner which is not apparently for carrying on in the ordinary course the limited partnership's activities or activities of the kind carried on by the limited partnership binds the limited partnership only if the act was actually authorized by all the other partners."

Limited liability is a concept whereby a person's financial liability is limited to a fixed sum, most commonly the value of a person's investment in a company or partnership with limited liability. If a company with limited liability is sued, then the plaintiffs are suing the company, not its owners or investors. A shareholder in a limited company is not personally liable for any of the debts of the company, other than for the value of their investment in that company. This usually takes the form of that person's dividends in the company being zero, since the company has no profits to allocate. The same is true for the members of a limited liability partnership and the limited partners in a limited partnership. By contrast, sole proprietors and partners in general partnerships are each liable for all the debts of the business (unlimited liability).

Although a shareholder's liability for the company's actions is limited, the shareholder may still be liable for its own acts. For example, the directors of small companies (who are frequently also shareholders) are often required to give personal guarantees of the company's debts to those lending to the company. They will then be liable for those debts in the event that the company cannot pay, although the other shareholders will not be so liable. This is known as co-signing.