IRREDUCIBLE CHARACTER DEGREES AND NORMAL SUBGROUPS by I. M. Isaacs and Greg Knutson KEYWORDS derived length, character degree, fitting subgroup DATE February 1997 STATUS Submitted to Journal of Algebra COMMENT Abstract Let N be a normal subgroup of a finite group G and consider the set cd(G|N) of degrees of irreducible characters of G whose kernels do not contain N. A number of theorems are proved relating the set cd(G|N) to the structure of N. For example, if N is solvable, its derived length is bounded above by a function of |cd(G|N)|. Also, if |cd(G|N)| is at most 2, then N is solvable and its derived length is at most |cd(G|N)|. If G is solvable and |cd(G|N)| = 3, then the derived length of N is at most 3.