Orthodontic systems and related methods are disclosed for designing and providing improved or more effective tooth moving systems for eliciting a desired tooth movement and/or repositioning teeth into a desired arrangement. Methods and orthodontic systems of the invention include tooth attachments having improved or optimized parameters selected or modified for more optimal and/or effective application of forces for a desired/selected orthodontic movement. Attachments of the present invention can be customized to a particular patient (e.g., patient-customized), a particular movement, and/or a sub-group or sub-set of patients, and configured to engage an orthodontic tooth positioning appliance worn by a patient, where engagement between the attachment and orthodontic appliance results in application of a repositioning force or series/system of forces to the tooth having the attachment and will generally elicit a tooth movement.