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Abstract. In the present study, the authors proposed a novel self-report 16-item scale for assessing individual differences in adult prosocialness and tested its measurement properties by employing an item response theory (IRT) analysis of data collected from a sample of 2,574 Italian adults. Prior work employing classical psychometric methods of analysis had already established the reliability and validity of the instrument. The present study furthered this scrutiny by examining whether the different prosocialness items were equally effective in discriminating people and equally informative; it also examined gender differences in the functioning of the items. The results of IRT analyses strongly supported the measurement effectiveness and sensitivity of the 16 prosocialness items, and findings are discussed for their implications in behavioral assessment research on prosocialness.

Self-and collective-efficacy beliefs were examined as main determinants of teachers' job satisfaction. In 103 Italian junior high schools, 2,688 teachers filled out self-reports to assess self-efficacy beliefs, their perceptions of the extent to which other school constituencies, namely, the principal, colleagues, staff, students, and families, were behaving in accordance with their obligations toward school wellfunctioning, their collective-efficacy beliefs, and their job satisfaction. Multilevel structural equation modeling analyses corroborated a conceptual model in which individual and collective-efficacy beliefs represent, respectively, the distal and proximal determinants of teachers' job satisfaction. The perceptions that teachers have of other constituencies' behavior largely mediated the links between self-and collective-efficacy beliefs. Collective-efficacy beliefs, in turn, partially mediated the influence that teachers' perceptions of other school constituencies' behavior exerts on their own job satisfaction.

Five studies document the validity of a new 8-item scale designed to measure positivity, defined as the tendency to view life and experiences with a positive outlook. In the first study (N = 372), the psychometric properties of Positivity Scale (P Scale) were examined in accordance with classical test theory using a large number of college participants. In Study 2, the unidimensionality of the P Scale was corroborated with confirmatory factor analysis in 2 independent samples (N₁ = 322; N₂ = 457). In Study 3, P Scale invariance across sexes and its relations with self-esteem, life satisfaction, optimism, positive negative affect, depression, and the Big Five provided further evidence of the internal and construct validity of the new measure in a large community sample (N = 3,589). In Study 4, test-retest reliability of the P Scale was found in a sample of college students (N = 262) who were readministered the scale after 5 weeks. In Study 5, measurement invariance and construct validity of P Scale were further supported across samples in different countries and cultures, including Italy (N = 689), the United States (N = 1,187), Japan (N = 281), and Spain (N = 302). Psychometric findings across diverse cultural context attest to the robustness of the P Scale and to positivity as a basic disposition.

Certain personality characteristics such as self-esteem, life satisfaction, and optimism are fundamental components of positive mental health status and well-being. There is consistent evidence that these traits tend to be substantially correlated in individuals. However, no previous studies have investigated the origin of such correlation. This research used the twin method to unravel the genetic and environmental architecture of self-esteem, life satisfaction, and optimism, along with their mutual interplay. The sample was derived from the population-based Italian Twin Register, and included 428 twin pairs, aged 23-24 years. Multivariate genetic modeling showed that genes influencing self-esteem, life satisfaction, and optimism are largely overlapping. Furthermore, results indicated that the environmental components of the traits may overlap only modestly, and suggested that a sizeable amount of variance in the traits may be explained by environmental effects specific to each of them.