<p>I've always been curious, how does it work? I thought you needed a Master's to try out for a PhD program. Or maybe this is just with some fields?</p>
<p>It depends entirely on the requirements of each program. In some fields, most programs will lean one way or the other in terms of allowing students to apply without a master's degree. In my field (bioengineering), most programs (at least the ones I was interested in) did not require an M.S. degree.</p>
<p>Also many programs allow for obtainign a Masters degree in the process of getitng the PhD. Often in these cases, TERMINAL masters degrees are not offered, but if you want to get one, you can take a masters exam or write a masters thesis and get one.</p>
<p>They are called direct phd programs. Many schools have them. A lot of times if you pass the qualifying exam but fail to complete your thesis, you will still get your masters.</p>