We (k;~,.c,ibe a set of rt,o(lttle.,i that together tuake up a grapheme-to phoneme conversion system for Dutch. Modules include a syflabificatiou program, a fast morphological parser, a lexical database, a phonological knowledg*: base, transliteration rules, and phonological rnles. Knowledge and procedures were intlflenmnted object-orientedly. We contrast GRAFON to recent p . t e r n recognitkm and rule. compiler approaches mid t i t to show that the first fails for languages with concatenative comlmtmding (like Dutch, Get,nan, and Scandinavian languages) while the second lack.,; the flexibility to model different phonological theories. It is claimed that sylhtbles (and not graphemes/phonemes or ulorphemes) should be central units in a rtde-based phonemisatkm algorithm. Furthermore, the architectnre of GRA!:"ON and its nser interface make it ideally suited as a rule testing tool fol phonologists.