Agarwal (mathematics, Florida Institute of Technology), Bohner (mathematics, U. of Missouri-Rolla) and Li (mathematics, Lanzhou U.) examine the qualitative theory of differential equations with or without delays. After an introductory chapter, the authors focus on first order delay and neutral differential equations, second order ordinary and delay differential equations, higher order delay differential equations, systems of nonlinear differential equations, and oscillation of dynamic equations on time scales. Although intended for graduate students and researchers in mathematics, physics engineering, and biology, mathematicians working in advanced time scale theory will also find this a useful reference.