The value of school screening for idiopathic scoliosis (IS) has been questioned recently, because of its high false positive referrals and its excessive cost, although in areas where screening programs exist, fewer patients ultimately require surgery for IS. In a typical school screening setting there are numerous factors which can determine the effectiveness. The present study identifies some of these factors and provides evidence based recommendations for the improvement of school screening effectiveness. After reviewing all the research papers which originated from the Thriasio school screening program and published in peer-review journals, specific suggestions for the organization, the optimal age of screening according to the geographical latitude, the best examined position, the standardization of referrals, the follow up of younger referrals with trunk asymmetry and the reduction of the financial cost are made. We strongly suggest the introduction of these recommendations to all the existing school screening programs in order to improve their effectiveness and to reduce the negative impact they may have on families and on the health system.