Abstract: A practice device for baseball pitchers which allows the pitcher to adjust size and location of the strike zone for varying degrees of difficulty. The pitcher's training aid includes an upright rectangular frame structure made up of a horizontal base structure, a vertical target support structure, and at least one non-vertical brace member. Two horizontal support members are slidably mounted on the opposing vertical sides of the target support structure thereby defining the boundaries of a strike zone through which a ball may pass. The vertical height of the strike zone is adjusted by manipulating the positions of the two horizontal support members along the sides of the target support structure. The strike zone has a first net contiguously attached thereto to catch all the baseballs pitched within the strike zone.The pitcher's training aid also includes a second net assembly which allows for adjustment of the width of the strike zone.