When a maritime worker is injured or killed, his legal rights and the obligations of those who may have caused the injury or death are determined by an analytical process that first defines the worker's particular employment function, and then determines which body of law governs the rights and obligations between the worker and the employer. This determination dictates both the rights of the worker against third parties and the employer's rights and obligations vis-a-vis third parties. Essentially, the maritime worker is placed into one of three categories: (1) a vessel crew member (loosely called a seaman), whose rights against his employer are determined by various statutes applicable solely to seamen, including most prominently the Jones Act, and by general maritime law which specifies certain duties owed to the seaman by his employer and third parties; (2) longshoremen, shipyard and repair workers, other harbor workers, and certain offshore workers covered by the Longshoremen's and Harbor Workers' Compensation Act (LHWCA); or (3) workers who, by virtue of the nature and location of their duties, have rights against their employer under state workers' compensation laws. Once a worker is put into one of the three categories, a determination of his rights against his employer and third parties is fairly straightforward since most of the major legal questions in that regard have been resolved. But the threshold question of determining the proper category in which the worker belongs is fraught with legal problems with which the courts and Congress have struggled, frequently at cross purposes, for much of this century. This Article will focus on the threshold categorization problem, with particular emphasis on that problem as it applies to terminal workers.