Purpose To determine how practicing physicians who graduated from internal medicine-pediatrics residency programs allocate their practice time and professional activities between adult and child patients, and to investigate whether there are predictors of the extent to which a particular physician's practice is more or less focused on one or the other of these patient groups. Method In 2003, the authors mailed a questionnaire to the 1,300 generalists and 472 subspecialists who, as of 2003, had completed internal medicine-pediatrics training since the inception of the program in 1980. Results The response rate was 73% for the generalists and 65% for the subspecialists. The vast majority of the generalist physicians stated that they provide care to all ages of patients. However, the proportion of care they provided to different age groups was not uniformly distributed, with more care provided to adults than children. Both generalist and subspecialist respondents were more likely to feel better prepared by their residency training to care for adults than for children. Those who felt less well-prepared to care for children were less likely to do so in their practices (odds ratio, 0.68; 95% confidence interval, 0.48-0.96). Fifty-four percent of the subspecialists pursued subspecialty training in internal medicine only, while 38% completed a combined internal medicine-pediatrics subspecialty program. These respondents, like the generalist respondents, also were more likely to focus clinical efforts on adults than children. Fewer than half (43%) provided any care to children zero to one year of age, while 54% provided at least some care to children aged two to 11 years. Conclusions Internal medicine-pediatrics physicians are more likely to spend a majority of their clinical care focused on adults and to perceive that they stay more current in the care of adults than of children. Potential reasons for this disparity may include training issues, greater reimbursement for the care of adults, perceptions of the impact on the medical market of the demographic shifts to older adults, and employment opportunities following training. These results also demonstrate the need for a more detailed and comprehensive assessment of the adequacy of pediatrics training in these programs.