Abstract: A vehicle towable cotton module compacter (10) is disclosed for use in the cotton field on seed cotton. A rigid framework (12) has upper and lower rectangular frames (28, 22). The upper frame (28) has a hopper (88) with an open top mouth (90). The hopper (88) has a collection box (92) with a push plate (96) for discharging collected cotton rearwardly through an opening (94) into a vertical compaction chamber (30). The chamber (30) is formed by a stationary vertical front wall (32) and a pair of L-shaped doors (40, 42) hinged along vertical axes at their forward edges. The longitudinal sides (44, 46) of the doors (40, 42) form the right and left sidewalls of the compaction chamber (30), and the lateral sides (48, 50) of the doors (40, 42) each form half of the rear wall of the chamber (30). The left, right and rear chamber walls are tapered outwardly as they extend downwardly. The upper frame (28) includes tamper means (108) mounted above the compaction chamber (30).