BACKGROUND Informed decision making regarding screening mammography is recommended for women in their 40s; however, what information women want and how much involvement in decision making they prefer are not known. METHODS Surveys were mailed to women aged 40 to 44 scheduled for their first screening mammogram. Women were members of a large New England health maintenance organization and received medical care at a multispecialty practice in the greater Boston area. Outcome measures included information needs and decisional control preferences. RESULTS Ninety-six women responded. Of 93 identifying their ethnicity, 62 (67%) were white, 18 (19%) were black, 10 (11%) were Asian, 2 (2%) were Hispanic, and 1 (1%) was other. Most (91% [85/93]) wanted their primary care provider to be the source of information regarding screening mammography. Information needs included the next steps to take if the mammogram result was abnormal (89%), how the woman would be contacted (75%), and how quickly (71%). Women also wanted to know about the harms of false-positive (84%) and false-negative (82%) results, benefits of screening in prolonging life (73%), and risk of getting breast cancer (69%). Most women preferred to make the screening decision after considering their medical provider's opinion (38%) or together with their medical provider (46%); fewer than 10% preferred that the decision be made by the woman or her provider alone. CONCLUSIONS Women cited specific information needs before initiating screening mammography, including screening logistics and potential harms and benefits of screening. They also wanted to participate in the decision-making process. Effective methods should be developed for communicating desired information before screening.