Two models of skill standards development and skill certification--the professional model and the skill components model--have been developed. Their development follows analysis of the skill standards movement and the 22 U.S. Departments of Labor and Education pilot projects developing skills standards for various industries. These two models differ along two critical dimensions--the conceptualization of skill and the role that workers play in the development and governance of the skill standards system. The skill component model is based on the limited, passive roles that workers are expected to assume in traditional hierarchical organizations. The concept of professionalism assumes that workers have the ability to apply general knowledge to a variety of nonroutine circumstances or situations. One of the crucial distinctions between skill standards as conceived under these two models is the ultimate purpose of the skill. In the skill components model, a list of skills indicates a set of specific tasks to be directed by someone other than the worker. In the professional model, a list of skills indicates a set of "enablers" that will enhance the worker's ability to carry out broader, autonomous responsibilities. An analysis of 21 pilot projects reveals a wide variation in practice. Many simply use already existing standards. Those that developed them base them on a skills component perspective. (Contains 10 references.) (YLB)