Abstract: Apparatus for converting a small trampoline into a ball player's pitchback device for the practice of pitching and fielding. Members fastened to the legs of the trampoline support it on an edge so that its resilient surface is presented at any of various desired angles to the pitcher. The members include a U-shaped supporting member having two parallel legs and a cross leg connecting the two legs at one end thereof. The other free end of each parallel leg is pivoted to a respective first and second trampoline leg. Two brace members are pivoted to a respective third and fourth trampoline leg. The parallel legs are selectively connectible to different locations along a respective brace member to adjust the angle of the trampoline.