Two multi-level studies were conducted to examine the effects of attitudes towards coworkers on daily well-being. Study 1 linked daily levels of coworker satisfaction to job satisfaction and life satisfaction and examined the extent to which job satisfaction mediated the relationship between coworker satisfaction and life satisfaction among 33 government employees. Study 2 replicated and extended Study 1 by examining the extent to which agreeableness moderated the relationships between daily levels of coworker satisfaction and job and life satisfaction among an occupationally diverse sample of 79 employees. Results revealed that coworker satisfaction varied significantly from day to day and was positively related to job and life satisfaction. Further, job satisfaction partially mediated the relationship between daily coworker satisfaction and life satisfaction. Finally, agreeableness moderated the relationship between coworker satisfaction and job and life satisfaction, such that daily levels of these variables were more contingent on coworker satisfaction for agreeable individuals. (Contains 2 figures and 6 tables.)