For Pittsburgh and Surrounding Areas
Group lessons for beginning and intermediate students are available through Pittsburgh's Calliope School of Folk Music. Check out their website (http://calliopehouse.org/school/) for the current class schedules. Private lessons are also available for students of all levels. Contact Acoustic Music Works (http://www.acousticmusicworks.com/) for further information.
Outside of Pittsburgh
For beginning students, there are a number of "teach yourself" books available from a large publisher, www.melbay.com. If you don't know how to read music, it's not a problem. Many beginning mandolin tutorials are written with both music, and with tablature - which is a numerical system that shows where to place your fingers on the strings. Most people find it helpful to also have an instructional CD or DVD that goes with the written tutorial.
For intermediate to advanced students, our friends at the Mandolin Cafe provide some good online tutorials. These can be found on their website at www.mandolincafe.com, under the "Lessons" section. They also provide a list of mandolin instructors, as well as a list of intensive mandolin workshops which are held throughout the year. If you can't find an instructor close to you, email us at firstname.lastname@example.org, and tell us where you are located. We may have some friends in your area, who might be willing to take on some students even though they do not advertise.