The seed planted in Ireland by St Malachy and St Bernard bore good fruit. In the thirty years that separated the foundation of Mellifont from the council of Cashel, the number of Cistercian houses effectively established had risen to fifteen, all save one of the filiatio Mellifontis. New rulers meant new patrons and nine Anglo-French houses were established in the half century or so after the Invasion. Within this same period there were ten further native Irish foundations (Map 4).

This was encouraging progress. Naturally it brought its problems. Chief of these was the one which faced the whole of the Irish Church at this time: the integration of the old with the new, the achievement of a modus vivendi between Irish and Anglo-French. The particular Cistercian experience of this general problem was to prove especially bitter.

The Irish Cistercian province, however, had its difficulties, even without the invader. In general terms, these problems were not in kind dissimilar from those which attended the exportation of a new and highly sophisticated monastic system from the relatively advanced civilization which had given it birth, to other remote and rude areas of Britain. In Yorkshire and Wales, as well as Ireland, Cistercian advance was striking, but it was not without incidents of strife and violence to mar its record. Mellifont itself took root in an atmosphere of intense native distrust of outsiders. The original community sent from Clairvaux c. 1140, included a number, perhaps a predominance, of French monks.