The smallest integer t for which the Wilson loop W(t) fails to exhibit area law is known as the confinement index of a given field theory. The confinement index provides us with subtle information on the vacuum properties of the system. We study the behavior of the Wilson and 't Hooft loops and compute the confinement index in a wide class of N = 1 supersymmetric gauge theories. All possible electric and magnetic screenings are taken into account. The results found are consistent with the theta periodicity, and whenever such a check is available, with the factorization property of Seiberg-Witten curves. (C) 2009 Elsevier B.V. All rights reserved.