There is no easy answer to this question. Opportunities for undergrad involvement in research change so rapidly in each lab that we can't keep up. Some faculty advertise openings for students here. Others post listings on the Career Learning Network site. Others may not advertise publicly at all. So, it's up to you, the student, to seek out the chance to participate in research. Don't get frustrated. Biology Department faculty members (potential supervisors) are approached by many more undergrads than they can possibly supervise. Thus, Biology Department faculty members must decline to offer to supervise some students every term. Generally, faculty members are highly motivated to work with promising young undergraduate researchers, but you should not believe that you are guaranteed the chance to work directly with one. The easiest way to begin your search for a potential faculty member is to scan the Biology Department faculty webpages to see which faculty member's research interests appeal most to you. It's best to identify several possible choices since any one may or may not have available spots in their lab. If you know any of the grad students in their lab (perhaps you've had them as a TA), speak with them. Perhaps they know of someone who would appreciate research help. Once you have done this, you should contact the faculty member to express your interest and/or ask for a chance to talk more. (A bit of advice: Make sure your e-mail correspondence reflects your particular interest in participating in research in THAT faculty member's lab. Faculty members often disregard blanket or broadcast e-mails from students.) If you're already volunteering as a research assistant it may be simple to enroll in a B98/B99. Just talk with your supervisor.