This paper traces the evolution and proposed merger of the two major advanced practice nursing roles, the clinical nurse specialist and nurse practitioner. The paper presents a review of the differences in the origins of the roles of the clinical nurse specialist and nurse practitioner, and analyzes the changes in these roles since the 1970's in Canada and the U.S. The positive and negative aspects of merging the clinical nurse specialist and nurse practitioner roles are also analyzed with respect to current issues and future trends. Changes in nursing roles, functions and education have occurred since the inception of the profession. Concurrently, there has been debate and conflict about the direction that these changes should take. Since the 1980's, the nursing literature has reflected these discussions, particularly with respect to the development of advanced practice nursing. The purpose of this paper is to review and analyze the differences in the origins of the roles of clinical nurse specialist (CNS) and nurse practitioner (NP), and to examine the benefits and costs of merging the roles.