Control Theory in the Plane This book introduces presents and illustrates the theory of control for systems governed by ordinary differential equations with special references to the two dimensional case. These systems are continuous finite dimensional deterministic with a priori bounds on the admissible controls. Its form is that of a graduate level textbook involving motivation a rather elementary level of exposition illustrative examples and extensive problem sections. It is addressed to applied mathematicians and engineers (system control electrical mechanical chemical) who wish to acquire further mathematical background in order to treat the subject they already know is both fascinating and important. Hopefully it might also serve those whose interest is in modeling bio mathematics and economics. The special feature of this book is the focused study in the second part of control systems whose state space is the phase plane. As with differential equations where specialisation to the plane provides a far richer theory (the classical results of Poincaré and Bendixson) control theory of two dimensional systems also has more intuitive and deeper results