<p>You can start by looking at their faculty rosters and course offerings.</p>
<p>While it may be unrealistic to expect a small LAC to have as many offerings each semester as a big research university, for a given subject, different small LACs may have varying numbers and types of courses offered. For subjects you are considering for a major, sufficient advanced offerings should be checked for; it does little good if the subject exists only to offer introductory level courses for students in other majors to take as breadth courses.</p>
<p>If you are extremely advanced in the subject you want to major in, undergraduate-only LACs may not be good fits at all, since highly advanced students may want to take graduate level courses as undergraduates (while skipping the introductory level courses where LACs have the biggest advantages in small faculty-led classes). However, this is mainly an issue for math majors who are two or more grade levels ahead (calculus BC as high school juniors or earlier).</p>