<p>There are general principles, like the odd freshman first semester inversion of priorities mentioned by singh2010, preferences for athletes, disabled student program members, class level and attained unit rankings, but also some old-fashioned randomization thrown in there. </p>
<p>yes, you can find someone in a lower class level ahead of you because of the randomization. Sometimes you come out ahead, sometimes you come out behind (the famous ‘screwed by telebears’ situation many will face one semester during their time at Cal), but you survive and move along towards your degree anyhow.</p>