For some time now I have delivered intermittent classes for adults on landmark Teshuvot in Iggerot Moshe. I am posting the sources, and in some cases linking to places elsewhere on this site where I have written up notes from the shiur, all for the free public use of anyone out there who may find them to be of interest or usefulness.
The Shiurim generally begin with the background information necessary to understand Rav Moshe’s position; then give Rav Moshe’s Teshuva or Teshuvot; then, when possible, offer arguments to Rav Moshe’s position from other contemporary Halachic personalities.
As the Shiurim were delivered on Shabbatot and holidays, there is no audio to post. If I ever give any of the classes again on weekdays, I will attach the audio at that time.

The Night Time is the Right Time: A Selichot Chronology     |     Notes and Sources

Got Spoiled Milk? – Rav Moshe on Chalav Yisroel     |     Sources

Thanks for Nothing: Rav Moshe on Thanksgiving     |     Notes and Sources

Mechitza, Part 1 – The Great Divide: Background and Basic Requirement     |     Sources

Mechitza, Part 2 – People with Glass Spouses Don’t Throw Tantrums: Explanations, Exceptions, and Extensions     |     Sources

Priorities in Mikvah Building: Shuls, Schools, and Where to Put Those Men     |     Notes and Sources