The specific aims of our study are to determine if (1) nonsteroidal anti-inflammatory drug therapy accelerates joint degeneration compared to analgesic medications; and (2) nonsteroidal anti-inflammatory drug therapy results in greater comorbidity and higher medical care costs and use compared to simple analgesic medication. To accomplish these aims, we will randomize 200 people with knee OA and 200 people with hip OA, defined by a Kellgren and Lawrence x-ray grade of 2 or 3, currently on NSAIDs, to either NSAIDs at their current dose or acetaminophen up to 4000 mg/day for 4 years.