The legal requirements for a man and a woman to marry vary from state to state. However, a marriage between a man and a woman performed in one state must be recognized by every other state under the Full Faith and Credit Clause of the United States Constitution.

Requirements set by state law can include:
- A marriage license issued by the county clerk or clerk of the court (along with payment of a fee).

- Both man and woman are 18 or older, or have the consent of a parent or a judge if younger.

- Proof of immunity or vaccination for certain diseases.

Many states have done away with mandatory premarital physical exams or blood tests. Some states still require for venereal diseases, and a few also test for rubella (also known as German Measles, a disease that is very dangerous to fetuses), tuberculosis, and sickle-cell anemia.

Due to the rise in HIV and AIDS, many states now require that people applying for a marital license must be offered an HIV test and/or must be provided with information on AIDS and tests available.

- Proof of the termination of any prior marriages by death, judgment of dissolution (divorce) or annulment.

- Sufficient mental capacity (often this is determined as the ability to enter into a contract).

Marriage requires two consenting people. If either person cannot or does not understand what it means to be married (due to mental illness, drugs, alcohol, or other factors affecting judgment), then that person does not have the capacity to consent and the marriage is not valid.

- The couple are not close blood relatives.

Close blood relatives cannot marry, although in some states, first cousins can marry. Of the states that allow first cousins to marry, a few also require that one of the cousins no longer be able to conceive children.

- Satisfaction of a waiting period from the time the marriage license is issued to the time the marriage ceremony is performed.

Most (but not all) states require a waiting period, usually from 1 to 5 days, between the time the license is issued and the time of the marriage ceremony. The purpose of the waiting period is to give a short time to cool off during which the parties can change their minds if they wish. The waiting period can be waived for good reason. For example, if the groom is arriving in the bride's town only one day before the wedding, but the state has a three-day waiting period, the waiting period probably can be waived by a judge or clerk of court.

26 states require couples to wait a few days after applying for a marriage license before they receive the license:

1-day waiting period: Delaware, Illinois, South Carolina

2-day waiting period: Maryland, New York

3-day waiting perid: Alaska, Florida, Indiana, Iowa, Kansas, Louisiana, Maine, Massachusetts, Michigan, Mississippi, Missouri, New Hampshire, New Jersey, Oregon, Pennsylvania, Tennessee, Washington

4-day waiting peiod: Connecticut

5-day waiting period: Minnesota, Ohio, Wisconsin.

- Performance of a marriage ceremony with witnesses and a person recognized by the state to have the authority to perform marriage ceremony (i.e. a priest, rabbi or a judge).

A religious ceremony should be conducted under the customs of the religion or, in the case of a Native American group, under the customs of the tribe. Religious ceremonies are normally conducted by religious officials, such as ministers, priests, or rabbis. Native American ceremonies may be presided over by a tribal chief or other designated official.

Civil ceremonies are usually conducted by judges. In some states, county clerks or other government officials may conduct civil ceremonies. Despite what many people believe, NO state authorizes ship captains to perform marriages.

Most states require one or two witnesses to sign the marriage certificate.

- Recording of the marriage license after marriage ceremony is performed. The person who performs the marriage ceremony must send a copy of the marriage certificate to the county or state agency that records marriage certificates. Failure to send the marriage certificate to the appropriate agency does not automatically nullify the marriage, but it may make proof of the marriage more difficult.

- Consummation of the marriage by the act of sexual relations (only a few states require this).

Most states consider a couple to be married when the ceremony ends. Lack of sexual relations after the ceremony does not automatically affect the validity of the marriage, although in some states non-consummation could be a basis for having the marriage annulled.

- A marriage that is performed in another jurisdiction, even in another country, is usually valid in any state as long as the marriage was legal in the jurisdiction where it took place.