A solid frame orthotic seating device for use in a sling seat that is supported by solid rails, such as a wheelchair. The solid frame orthotic seating device comprises a solid, rigid, non-collapsing, and durable interior skeletal frame with an elevated anterior wedge sloping down to the top surface of the frame, lateral well support arms, and a posterior well. The frame dimensions are designed to place the user's hips into flexion, position the user's pelvis in a neutral to anterior position, and position the user's buttocks into and or below the posterior well. The anterior wedge supports and distributes the weight of the user's body away from the buttocks. The strength and design of the solid frame uniquely promotes proper positioning, and helps to anchor the user by positioning their buttocks into and or below the posterior well and or below the solid lateral well support frame.