The Trichotomous Achievement Goal Scale was developed by Agbuga and Xiang (2008) by including selected items from the scales of Duda and Nicholls (1992), Elliot (1999), and Elliot and Church (1997) and adapting them into Turkish. The scale consists of 18 items, and students rated each item on a 7-point Likert scale. To ascertain the validity and reliability of the Trichotomous Achievement Goal Scale, it was administered to 845 female and 861 male Turkish high school students attending three public schools in the 2008-2009 spring semester. Exploratory and confirmatory factor analyses were conducted, and Cronbach's alpha and Fornell and Larcker's (1981) criteria were tested on the items that measured the students' achievements, screening for the three distinct types of achievement goals proposed by the trichotomous framework. Based on the results of the study, the 16-item Trichotomous Achievement Goal Scale can be claimed as a valid a reliable scale. (Contains 1 figure and 3 tables.)