C.R.S. § 19-5-201

Any child legally available for adoption as provided in section 19-5-203 , under eighteen years of age, and either present in the state at the time the petition for adoption is filed or under the jurisdiction of a court in Colorado for at least six months may be adopted. Upon approval of the court, a person eighteen years of age or older and under twenty-one years of age may be adopted as a child, and all provisions of this part 2 referring to the adoption of a child shall apply to such a person.