The legal age to marry in Colorado without parental consent is 18 years of age. However, your question suggests that you may be concerned about other barriers to marriage. There are requirements, in addition to age of majority, that relate to a person's ability to enter into a valid marriage. For instance, neither of you can be married to someone else at the time you seek to marry one another. Neither of you can enter the marriage as a joke or on a dare. You and your prospective spouse cannot be brother and sister. Both of you must have the mental capacity to consent to the marriage. These are only a few of the requirements for a valid marriage in Colorado. Therefore, you should consult with an attorney about your particular circumstances.