This paper represents an investigation of the broad factors which underpin the success of second-level schools in terms of the proportion of their "sits" who proceed to third-level education and, also, in terms of the "quality" of their educational destinations. It distinguishes between three school types: public (non-fee paying, English language) private (fee paying, English language), and "Gaelscoil" (non-fee paying, Irish language). Both private schools and the "Gaelscoileanna" reported much better results than public schools. The paper disentangles the nature of this advantage by investigating the extent to which the private school and "Gaelscoil" advantage over public schools was predicated on better circumstances and/or on better responses to circumstances. Our results show that private schools and the "Gaelscoileanna" had a response advantage over public schools: if private schools and the "Gaelscoileanna" were constrained to responding to their circumstances in the manner in which public schools responded to theirs, the performance of private schools and the "Gaelscoileanna" would suffer. By constraining the coefficient responses of all three types of schools to be that of public schools, we arrive at a revised list of the "best performing" 25 feeder schools in Ireland. This is different from, but not dissimilar to, a ranking of the best performing 25 schools based on their raw performance. (Contains 31 notes and 14 tables.)