Engel Subalgebras of Affine PI Algebras Lance SMALL Abstract: It is shown that a weakly Engel Lie subalgebra of an PI algebra is nilpotent. This result is a consequence of the following theorem: Nil subrings of endomorphism rings of of finitely generated module over affine PI algebras are nilpotent. These results are joint with Robert Guralnick and Efim Zelmanov.