Conducted 3 experiments with a total of 234 male Holtzman rats. Results indicate that permitting Ss to run in either of 2 directions to avoid shock (any-way training) resulted in performance superior to that of 1-way or 2-way avoidance. In the any-way condition, Ss often selected a bidirectional mode of responding. Exposure to signaled inescapable shock enhanced avoidance in all avoidance modes. Any-way training enhanced subsequent 2-way avoidance to a greater extent than did 1-way training. Results are interpreted in terms of the need to learn directional responses in avoidance training, role of response initiation in modifying avoidance behavior, and the effectiveness of running responses in determining avoidance performance. (18 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)