This document discusses several theories of career development. It begins by explaining that vocational counseling should be an integral part of education to help students choose careers. It then summarizes some important contributors to vocational counseling theory, including Frank Parsons who is considered the founder of the field. The document outlines several major theories of career development such as Holland's theory involving six personality traits. It concludes by discussing Parsons' influential three-part model of understanding yourself, knowledge of different careers, and relating the two.