There is a paucity of research on motivation and education in developing countries. Although psychological constructs relating to academic engagement and achievement have been identified and researched in a number of cross-cultural settings this body of research has rarely been extended to the developing world. The processes by which students from majority, indigenous and under-developed nations are motivated in school are unclear. The current research sought to identify what motivates students from such demographics by investigating the psychometric properties of two instruments measuring student motivation. Three-hundred and fifty-five students from Papua New Guinea completed the Inventory of School Motivation and the General Achievement and Goal Orientation Scale. These instruments measured students' endorsement of academic (mastery and performance) and social goal orientations. Results supported the a-priori factorial structure and reliability of the instruments and deemed them to be satisfactory and useful measures of motivation in Papua New Guinea. Results are discussed in the light of motivational goal theory. (Contains 5 tables.)