Reciprocal associations between the Big Five personality traits and parenting stress -including both parents' feelings of their distress and perception of their incompetence as parents -were studied with 248 participants (49% of which were males). Longitudinal data, collected at ages 33/36, 42, and 50, were used. Cross-lagged path analysis revealed that in case of both mothers and fathers, neuroticism at age 33 predicted high parenting stress and extraversion at age 33 low parenting stress at age 42. Also, parenting stress at age 36 predicted high neuroticism and low extraversion at age 42. From age 42 to 50, only high parenting stress contributed to low neuroticism. Thus, more significant cross-lagged associations of neuroticism and extraversion with parenting stress were detected in early middle age, i.e. from age 33/36 to 42, as compared to later midlife, i.e. from 42 to 50 years of age. The reciprocal associations between parenting stress and neuroticism and extraversion were similar for both mothers and fathers. High conscientiousness at age 42, however, predicted low parenting stress at age 50 only in fathers.Keywords: personality, parenting stress, longitudinal, cross-lagged path analysis 3 Longitudinal Study on Reciprocity between Personality Traits and Parenting Stress Personality traits refer to relatively stable emotional, cognitive, and behavioral differences among individuals across a variety of situations. They have empirically been found to show high consistency across adulthood (e.g., McCrae & Costa, 2003;Roberts & DelVecchio, 2000;Rantanen, Metsäpelto, Feldt, Pulkkinen, & Kokko, 2007;Terracciano, Costa, & McCrae, 2006).Because of this consistency, personality traits are claimed to shape adult development through the way in which "individuals experience, interpret, and respond to the developmental tasks they face across the life course" (Caspi & Shiner, 2006, p. 339). Conversely, social roles that individuals adopt during the life course may induce personality changes since, along with new roles, individuals are often confronted with social expectations that require adaptation and a more mature personality-that is, one characterized by low neuroticism (i.e., high emotional stability), high agreeableness, and high conscientiousness (Roberts, Wood, & Caspi, 2008;Roberts, Wood, & Smith, 2005), although Staudinger (2005) emphasizes this combination of personality traits as referring more to personality adjustment than to growth or maturity. For example, using longitudinal data on women and men at college entry and four years later, Robins, Fraley, Roberts, and Trzesniewski (2001) showed that young adults became more agreeable, conscientious and emotionally stable, implying increased levels of adaptation and psychological functioning, during this developmental transition. Similarly, engaging in a serious partnership for the first time in young adulthood was found to be associated with decreased neuroticism and increased conscientiousness (Neyer & Asendorpf, 2001). In addition to entering the ...