Contingent vs. Vested: In simple terms, a future interest is contingent if something must occur (a “condition precedent”) before we can know certain things about the ultimate disposition of the interest. Typically the condition precedent will be (i) the absence of any ascertainable person who might receive the interest – e.g., a gift to unborn children, the condition is the need to be born; AND/OR (ii) some event that must happen before the future interest can become a possessory interest – e.g., in the following example, the need to graduate from law school.
Consider: “to A for life, then to A’s first child who graduates from law school.” The future interest is the “remainder” given to A’s first child who …. Assuming that A has no children at the time of the grant, the future interest here (a remainder in A’s first child …) is contingent. The remainder becomes “vested” when a child of A (having been born) graduates from law school.