Spanish Journal of Psychology (2013), 16, e47, 1–9. © Universidad Complutense de Madrid and Colegio Ofcial de Psicólogos de Madrid doi:10.1017/sjp.2013.35 The Perceived Stress Scale (PSS; Cohen, Kamarak, & Mermelstein, 1983) is one of the most widely used measures for evaluating stress (Pedrero & Olivar, 2010). However, the manner in which stress is evalu- ated depends on the framework that is used to defne it. Currently, the most common models of stress are process models, which are based on the transactional theory of stress (Lazarus & Folkman, 1984). This theory regards stress as a transactional relationship between the individual and his environment. In this approach, the stress response is activated when the individual views the situation (stressor) as taxing his resources and threatening his well-being. Evaluating the situation as a threat, harm, or challenge triggers the characteristic stress response at the physiological and behavioral level. This perspective is consistent with the PSS, which was designed to measure the degree to which life situ- ations are perceived as stressful (Remor & Carrobles, 2001). There are 3 versions of the scale: the PSS14, the PSS10, and the PSS4 (Cohen & Williamson, 1988). The numbers that follow the acronym indicate the number of scale items, and the PSS14 is the most widely used version. The original English version of the PSS14 has been adapted into many languages, and there are Dutch, Hebrew, Greek, Italian, German, French, Bulgarian, Hungarian, Korean, Chinese, Taiwanese, Thai, Polish, Turkish, and Russian versions, as well as Spanish versions adapted for Spain, Chile, Puerto Rico, and Mexico, which can be viewed and accessed at the web page for the Laboratory for the Study of Stress, Immunity and Disease at Carnegie Mellon University (http://www. psy.cmu.edu/∼scohen/scales.html). González and Landero (2007) adapted the Spanish version of the PSS (Remor & Carrobles, 2001) for its use in Mexico. This scale exhibits adequate internal consis- tency and exploratory and confrmatory factor analyses confrmed the two-factor model reported by Cohen and Williamson (1988). The two-factor structure of the PSS14 (with two factors that group positive and negative items, respectively) has been confrmed for other countries, such as Japan (Mimura & Griffths, 2008), Colombia (Campo-Arias, Bustos-Leiton, & Romero-Chaparro, 2009), and Spain (Pedrero & Olivar, 2010). The availability of different language versions of the PSS makes it possible to obtain stress scores and com- pare stress levels in widely diverse samples. However, for most versions of the PSS, there are no normative data or applications for large samples. Recently, Cohen and Janicki-Deverts (2012) presented normative data for the United States based on samples from 1983, 2006, and 2009. This work motivated the present study, which collected data in Mexico. The goal of the present study was to obtain normative data regarding gender and different age groups based on a sample of 1990 Mexican participants to validate the underlying factor structure of the construct. The Perceived Stress Scale (PSS): Normative Data and Factor Structure for a Large-Scale Sample in Mexico Mónica Teresa González-Ramírez 1 , María Noel Rodríguez-Ayán 2 , and René Landero Hernández 1 1 Universidad Autónoma de Nuevo León (Mexico) 2 Universidad de la República (Uruguay) Abstract. One of the most widely used scales for the evaluation of stress is the Perceived Stress Scale (PSS), and it has been adapted into different languages. However, few studies have presented normative data from large samples, and there do not appear to be any studies of the PSS that provide normative data based on large samples for Mexico. Thus, the goal of this study was to provide normative data regarding gender and different age groups for a sample of 1990 Mexican subjects to validate the factor structure of the construct for this sample. The analysis of the 10- and 14-item versions of the PSS revealed that the scale had adequate reliability and that the factor structure was consistent with previous studies. With respect to the normative data, the means of the different groups ranged from 20.93 to 25.63 for the PSS14 and from 14.52 to 17.73 for the PSS10. We propose that scores within one standard deviation of these means be used as reference values for each group. Received 18 October 2011; Revised 18 February 2012; Accepted 13 March 2012 Keywords: Perceived Stress Scale, Mexico. Correspondence concerning this article should be addressed to Mónica Teresa González-Ramírez. Dr. Carlos Canseco 110. Col. Mitras Centro. 64460. Phone: +52-8183338233. Monterrey. Nuevo León. (México). E-mail: monygzz77@yahoo.com or monica.gonzalezrz@uanl.edu.mx