Delaware law prohibits employers with four or more employees, employment agencies, and labor organizations from discriminating against or refusing to hire an individual on the basis of race, marital status, genetic information, color, age, religion, sex (including pregnancy), sexual orientation, national origin, or gender identity unless the characteristic is a bona fide occupational qualification (BFOQ). Employers with 15 or more employees are also prohibited from refusing to hire or recruit a qualified person with a disability.
Therefore, although there is no specific prohibition of employment advertisements expressing a preference or limitation regarding one of these characteristics, it seems clear that to do so would violate the law. However, an employer is not prohibited from hiring an individual on the basis of religion, genetic information, age, sex, or national origin if the characteristic is a BFOQ reasonably necessary to the normal operation of the business (DE Code Tit. 19 Sec. 711; DE Code Tit. 19 Sec. 724).
Religious corporations, associations, or societies are generally excluded from the provisions regarding sexual orientation and gender identity.