Many people desire to adopt children who are in need of loving homes, but age complications can scare parents from jumping into the adoption process. Nowadays, many individuals are considering adoption as they near their 40s or 50s. This is often because they put off starting a family until they are financially secure and set in a career path. Also, some couples will try years of infertility treatments before deciding to adopt. Parents may want to create a second family after a late remarriage, or have young ones in the home again after their first set of children are grown and gone.

When it comes to domestic adoption, there is not a federal age requirement. Because birth parents are often involved in selecting a family for their child, they can determine whether or not they think applicants are "too young" or "too old." Some adoption agencies operate by the the "40-year rule of thumb" to determine an age range. This guideline states that parents who are 40 years older than their child should not adopt. Slowly, this rule is changing as the Baby Boomer generation alters the government's perspective on the limits of older adults. Now, health, physical fitness, and mental stability all factor into age determination. Currently, some agencies are encouraging older adults to adopt infants, regardless of the original rule which would make them invalid candidates. Men and women over 40 can also adopt older children who have grown up in the foster care system. Older parents are also encouraged to take on special needs children, because their past parental experiences help to equip them with the tenacity to face challenges. Still, parents over 40 are not normally put high on the priority list for adoptions in the United States. A domestic adoption may take years and involve hefty fees.

Kinship adoption allows men and women well into their sixties or higher to adopt their grandchildren or nieces and nephews. These adoptions usually come about from a family emergency, and are carefully regulated. These adoptions are not as formal as a domestic one between strangers and the government will usually allow special exceptions to age limits if it is in the child's best interest. Because the adoptive parents are related to the child, it is much easier to obtain clearance.

Prospective parents can also adopt internationally. According the American Bureau of Consular Affairs, 11,059 Americans adopted children from other countries in 2010. On the United States side, an adoption applicant must be at least 25 years old to adopt internationally if he or she is unmarried. A social worker will interview prospective adoptive parents and determine their suitability, including criminal background checks, fingerprinting, and home studies. If a person's age hinders them from being a suitable parent, then that may affect their position. Normally, this "age" is more contingent on the prospective parent's health and vitality than the amount of birthdays he or she has had.

Certain countries have created their own adoption age limits. Most foreign adoption agencies work within the age range of 25-45 years, especially if parents are seeking an infant referral. In China, parents must be over 30 and under 50 to adopt. India has one of the smallest adoption age windows, only allowing parents between the ages of 28-40. Many countries, including Poland and Korea require that adoptive parents be under 44. In Cambodia, Nepal and Peru, new parents must be less than 55 years of age. In Mexico, Russia, and Greece, couples need to be less than 60 years old. Some countries also have stipulations on age that are contingent to marital status. For example, a single man who is seeking to adopt an infant in China must be over the age of 40 to do so. Certain agencies and countries also have rules about the total age of both parents. This allows regulation on parents that are of very different ages. If a parent does not meet any of these age requirements, some countries have no stipulations on adoption, such as Russia, Taiwan, Vietnam, and Ukraine.