There are differences in organizational architecture between union and non-union construction firms in early 1990s. The construction industry has traditionally been dominated by strong union firms. However, non-union construction firms began to emerge in the 1990s and this change caused to bring conflicts between union and non-union construction firms. This presents a unique opportunity to study employees' attitude toward organization. This article investigates workers' attitudes toward union and non-union construction firms in terms of organizational commitment (OC) and turnover intention. Control variables in OC and turnover intention include personal characteristics, job characteristics, group−leader relations and organizational characteristics. The study found that employees in union firms are more committed to the organization than non-union organization, but they have higher intention to job turnover although the regression coefficients of union variable in commitment and turnover intention are not statistically significant at the conventional level of significance.