The focus of the present study lies on optimism and its relationships to the components of subjective well-being, i.e. global life satisfaction, positive affect and negative affect. We investigated the direct and indirect (via affectivity) effects of optimism on global life satisfaction in the Swedish middle-aged women at two time points (age 43 and 49), and in the Lithuanian middle-aged women. For this purpose, structural equation modelling was used and the fit indices were compared between two cognitive-affective models. The best fitting model suggests that the direct effect of optimism on global life satisfaction is stronger than that via affectivity. The result was found both in the Swedish sample at two time points and in the Lithuanian sample where the indirect effect was very low and insignificant. The indirect effect via negative affectivity was significant in the Swedish samples at both time points while the indirect effect via positive affectivity was low but significant only in the Swedish sample at age 43. In further analyses we studied the stability of optimism and the components of general SWB in the Swedish sample over a six-year period and a mean difference in optimism in two samples of women, Swedish and Lithuanian. Data analyses showed varying stability of the studied concepts with the highest stability coefficient being for negative affect and the lowest being for global life satisfaction. Cross-cultural analysis of mean difference in optimism showed that the Swedish women at age 43 reported significantly higher optimism as compared to their Lithuanian counterparts.