Osteoporosis is a condition in which bones become less dense and bone fractures occur more easily. Osteoporosis is especially common in women after menopause. However, men also get osteoporosis as they age and can have osteoporosis-related fractures. Two approaches can be used to prevent fractures from osteoporosis. One is to promote measures that prevent osteoporosis, such as adequate calcium and vitamin D intake, physical activity, and avoidance of tobacco and alcohol. Some drugs (bisphosphonates) can also prevent osteoporosis, but they are not recommended for general use because of side effects and expense. The second approach is to screen for osteoporosis. Screening means identifying persons with low bone thickness before they have a fracture. Those at high risk for fracture will benefit most from drugs that prevent fracture. Testing for osteoporosis involves measuring how dense bones are with a test called dual-energy x-ray absorptiometry (DXA). Dual-energy x-ray absorptiometry is a painless and noninvasive test that utilizes an open machine and uses x-ray beams to measure soft tissue and bone thickness. Newer tests involve the use of other x-ray techniques and ultrasonography. The U.S. Preventive Services Task Force recommends bone thickness testing for women age 65 years or older and testing at younger ages for women who have risk factors for osteoporosis. However, it is uncertain whether men should also be screened for osteoporosis, so the ACP wanted to develop recommendations for screening in men.