Purpose: Despite the benefits of the SDM model, many patients do not attain the level of participation they desire. The purpose of this study was to gain a more complete understanding of the essential elements, or the prerequisites, critical to active patient participation in medical-decision making from the patient's perspective. Methods: Individual, in-depth, patient interviews were conducted until thematic saturation was reached. Two analysts independently read the transcripts and jointly developed a list of codes. Results: 26 subjects were interviewed; mean age = 61 (range 49-76), 100% Caucasian; 50% college graduates. Six elements were repeatedly described as being essential to enable patient participation in SDM: 1) Knowledge: “They asked me how do you like this or what do you think of that, and I would usually say - I will take your advice - because the average person knows nothing”; 2) Encouragement of participation by physicians: “I feel like I can question things that my doctor says, if I don't understand I can ask him about it so that I can make an informed decision”; 3) Appreciation of the patient's responsibility to play an active role: “A patient has to be involved. It's their body and they are the ones who are going to be carrying out whatever decision's been made”: 4) Awareness of choice: “I don't think I had a choice. I thought I had to do what the doctor wanted me to do”; 5) Time: “It just doesn't feel like there's ever room in the system anymore for real dialogue. In other words, that's what gets in the way. Time sadly”; and 6) Readiness to participate: “I'm one of these people that have to think the whole thing out. I don't like to make decisions like that on the spur of the moment”. Conclusions: Our findings have important clinical implications and suggest that several needs must be met before patients can become active participants in SDM. These needs include ensuring that patients: 1) “buy in” to the importance of active patient participation, 2) understand the trade-offs related to available options, and 3) have the opportunity to discuss these options with their physician in order to arrive at a decision concordant with their values.