New American Bible. Outline from the NAB:
Address (Gal 1:1-5)
Loyalty to the Gospel (Gal 1:6-10)
Paul's Defense of His Gospel and His Authority (Gal 1:11-2:21)
Faith and Liberty (Gal 3:1-4:31)
Exhortation to Christian Living (Gal 5:1-6:10)
Conclusion (Gal 6:11-18)