The diligent working attitude of Taiwanese employees has created miracle in Taiwanese economy. The result of investing too much time in their career does not only affect their psychological well-being but also impact their family dynamic. According to some researches, working overtime does not always bring benefit to the organizations; nevertheless, working overtime is still a widespread phenomenon even though there are labor laws to regulate such behavior in Taiwan, Karoshi is quite common on the news. This research samples knowledge workers to investigate the relationship between employees¡¦ motivations, cognitions, and behaviors of working overtime; the moderating effects specific to job characteristic will be studied as well. Furthermore, we have identified the motivations for work overtime into three main categories: immediate rewards, seeking for career growth potential, and peer pressure from other employees. The first category is immediate rewards, which simply referred to overtime pay or extra vacation days employees earn from working overtime. The second category of motivations to work overtime is to seek for a career growth potential in the near future. By working overtimes, the employees hope the employers can see the dedication employees had put into their work then provide employees opportunities to move onto a higher level position or an increase in compensation. Peer pressure is the third category of motivation for people to work overtime. The employees feel pressure to be the first one to step out off the office while others are still working after their regular work hours. In addition, this research also analyzed the relationship between work performance evaluations and emotions associated with overtime; identifying specific behaviors associated with working overtime by analyzing the relationship between how man overtime hours worked and how often one will need to work overtime. By doing this research, we hope that we hope we can provide a better understanding of the extended hours overtime phenomenon in Taiwan. Through the real example analyses, this research acquires the following results: 1.There is no obvious relation between seeking a career growth potential and employees¡¦ feeling toward overtime; nor there direct connection between motivation for overtime and emotions which associated with working overtime. 2.However, our real example analyses do show a positive relationship between motivation due to peer pressure for working overtime and work performance evaluation for overtime. Nerveless, the research data shows a inverse relation between motivations due to peer pressure for working overtime and emotions associated with working overtime. 3.There is a positive relationship between seeking a career growth potential and hours worked. 4.If one is concerned his/her evaluations from his/her supervisor, then there will be an obvious increasing in his/her overtime working days and hours but there is no connection with the work emotions. 5.The individual control of work will cause negative interference with the motives and the evaluations of overtime working; the feedback and the integrity of work will cause positive interference.