The International Classification for Nursing Practice (ICNP^®) has been developed as a 'unifying framework' for comparing and combining disparate nursing data from across the world. In order to meet the increasingly sophisticated needs of users of ICNP^®, substantial revision has been made to the Beta 2 version of ICNP^®, culminating in the launch of ICNP^® Version 1 in 2005. In its revision of ICNP^®, the development team has followed a rigorous development process using current best practice in ontology development. The core of ICNP^® Version 1 is represented in the Web Ontology Language, the de facto standard ontology representation language. An ontology editor, Protégé, and other software tools have been used to support the process. The result is a robust terminological resource that can accommodate existing and emerging nursing terminologies and allow comparisons to be made between disparate nursing data. The revision has provided ICNP^® with a sustainable foundation that will a) facilitate further development and maintenance of ICNP^® and b) extend significantly its functionality.