Caribbean Journal of Psychology: Vol. 7, No. 1, 2015 64 The Susceptibility to Online Peer Influence - Sexual Risk Scale: Preliminary Evidence of Validity Mia A. Jules Donna-Maria B. Maynard University of the West Indies, Cave Hill Neil Coulson University of Nottingham, United Kingdom Abstract This article discusses the preliminary processes in developing and validating a measure of susceptibility to online peer influence involving sexual risk taking behaviours in emerging adults on the social networking site Facebook. The Susceptibility to Online Peer Influence – Sexual Risk Scale (SOPI-SRS) was developed through a sequence of steps, including a review of the literature and input from experts. The scale was administered to 241 undergraduate students in Barbados to explore the factor structure. Item analysis reduced the scale from 13 to 11 items. Items with the highest reliability were retained. A nomological network was also created in order to gather evidence of construct validity. Results of exploratory factor analysis of the scale revealed the presence of three components, each of which produced a reliability coefficient of 0.69 or higher. Qualitative inspection of the factors that emerged from the final 11 items of the SOPI-SRS suggested the presence of three subscales: (1) activities involving explicit bodily exposure of self and/or peers online, (2) activities which may lead to sexually explicit behaviour offline and (3) endorsement of friend-produced sexual media content online. Internal consistency for the overall scale (α = 0.76) was strong and correlations assessing validity were significant in the theoretically expected directions. Limitations and implications for future research are discussed. Key words: Online, Sex, Risk, Peer influence, Emerging adulthood Correspondence concerning this article should be addressed to Dr. Mia A. Jules, The School of Education, and The University of the West Indies, Cave Hill Campus, Barbados, and Email: Mia.Jules@cavehill.uwi.edu. We would like to acknowledge the Commonwealth Scholarship Commission, The Office of Graduate Studies and Research, University of the West Indies, Cave Hill Campus and the University of Nottingham, United Kingdom for supporting and endorsing this project financially and technically. We would also like to thank the University of the West Indies for its invaluable support, as well as the other collaborators, advisors, and students who participated in the research. Received June 2015 Accepted December 2015