One of the main functions of the dental pulp is the formation of dentin. When the pulp undergoes pathological changes before complete root development, normal root growth is disrupted. If the pulp is reversibly inflamed due to caries or exposure, the treatment of choice is to maintain pulp vitality by pulp capping or pulpotomy. If the pulp is irreversibly inflamed or necrotic, traditional apexification procedures consist of multiple and long-term applications of calcium hydroxide in order to create an apical barrier that aids in root canal obturation. Recently, artificial apical barriers using mineral trioxide aggregate (MTA) have been introduced. In addition, pulp regeneration (revascularization) has received attention as an option for such teeth. That topic will be addressed in the next chapter. In this review, we will give a brief description of the embryology of root development, major causes of pulpal inflammation, factors affecting treatment planning, and tests for diagnosing pulpal conditions. This will be followed by a comprehensive literature review from 1908 through June 2010 regarding the definition, history, materials used, animal and human studies, mechanisms of action, prognosis, as well as advantages and disadvantages of apexogenesis by pulp capping and pulpotomy.