Single males who want to adopt a child can expect to be met with a lot of suspicious looks from case workers both domestically and internationally. Single males who want to adopt a female child will be under even more of a close watch. Even with the changing laws concerning gay adoption in many states, it can be years and years before a single male gets his foot in the door for an adoption opportunity. It's not that single males are necessarily bad, but men are traditionally thought to be less nurturing than a woman and more physically driven when it comes to punishment and expression. While these are obviously gross generalizations of the male psyche, single male adoption is what it is.
A single man's best shot at adopting will be of a young male who is thought to be in need of a strong male role model in his life. A man can find such children by seeking out the help of social workers. A man who has his heart set on adopting a daughter may increase his chances of adopting by passing his home study before he registers with agencies.
Note: In China, a single male has to be at least 40 years a girl's senior before he is eligible to adopt her. If a man is openly gay and expresses this to his agency, this may increase his chances of adopting in certain states. States like Florida, however, ban any gay adoption.