PSU has a post-baccalaureate (post-bac) program for students who already hold a bachelor's degree but wish to take further courses for credit. This program is primarily intended for students who wish to earn a second bachelor's degree in a new field. The requirements to graduate with a second bachelor's degree are the same as the departmental requirements for the bachelor's degree; the "general" University requirements are waived, so the post-bac degree takes less time to complete. (It can be completed in about two and a half years of full-time work by a student with a technical background.)
The post-bac program is also useful to prospective graduate students who wish to take undergraduate and/or graduate classes to prepare for application to the graduate program.
There are advantages to obtaining post-bac status as opposed to just taking courses as a non-admitted student: you can register for more credits per quarter, and you register for courses before non-admitted students. Post-bac students taking only undergraduate courses pay undergraduate fees. If you take one or more graduate classes in a given quarter, then you pay graduate fees for all classes during that quarter.
To obtain post-bac status you must formally apply to the University by completing the post-bac application, which is available from the Admissions Office. Admission to the post-bac program is not competitive; it is normally given if you hold a four-year undergraduate degree from an accredited institution. You must also have a cumulative GPA of 2.00 (2.25 for nonresidents) for any work taken after your bachelor's degree.
A slideshow presented at the post-bac information session can be found here