Most Wills created for individuals who own significant assets provide for "Descendant's Trusts" for children, grandchildren and other descendants. Some Wills include "Child's Trusts" for children only. Others include Child's Trusts for children and Descendant's Trusts for grandchildren and other descendants. Both trusts for children and trusts for grandchildren and other descendants can be called, "Descendant's Trusts." In any case, each child or other descendant is the named primary beneficiary of his/her own separate trust. The beneficiary's own children and other descendants are often included as additional (secondary) beneficiaries of the primary beneficiary's Descendant's Trust to whom distributions can be made while the primary beneficiary is living. This adds flexibility and increases the income tax options. When the primary beneficiary dies, the assets remaining in his/her Descendant's Trust will usually be distributed to new Descendant's Trusts for his/her children, but it is typical to give the primary beneficiary of a Descendant's Trust a testamentary power of appointment (see below).

In Wills without second generation planning, "Contingent Trusts" are used (see below). Contingent Trusts terminate when the beneficiary reaches the specified termination age (such as age 25). Until the Contingent Trust terminates, the trust protects the beneficiary, just like a Descendant's Trust. However, when a Contingent Trust terminates, all of the protections are lost. In contrast, Descendant's Trusts continue the benefits of the trust structure for the beneficiary's entire life (and, often, for the lives of the beneficiary's children and grandchildren, too).