Two significant differences were found between theoretical expectation and empirical results to budgetary slack in managerial accounting study. First, subjects under the slack-inducing pay schemes set their budgets well above zero regardless of their risk-neutral or risk-averse characteristics, although their maximum rewards arise from setting their budgets at zero (Waller, 1988; Chow, Cooper, and Waller, 1988; Chow, Cooper, and Haddad, 1991). Second, theoretically subjects operating under truth-inducing pay schemes set budgets at their best estimate performance, that is, no budgetary slack. But in violation of traditional economic theory, truth-inducing pay schemes have not been found to drive all slack out of the budget (Chow, Cooper, and Haddad, 1991). These results suggest that the existence of other non-pecuniary factors impacting slack, such as personal integrity and conscience, or social pressure (Chow, Cooper, and Waller, 1988). Moreover, the other potential causes in methodology may affect the congruence with theoretical expectation: (1) single-period experimental setting may limit the subjects¡¦ learning effect (Chow, Cooper, and Haddad, 1991), or (2) social pressure that was not controlled between subjects results in measurement errors. This study investigates the impacts of pay scheme, social pressure, internal norm and organizational commitment on budgetary slack in the participative budgeting setting. Specifically, this research executes an experimental test of the effects of a truth-inducing pay scheme, superior-generated social pressure, and subordinates¡¦ intern norm and their organizational commitment on the propensity to set their budgets below expected performance. In the experimental setting budgets were participatively set under three kinds of pay scheme and under the condition of either existence of social pressure or no social pressure. Pay schemes are categorized by three factors: truth-inducing pay scheme, fixed-pay-plus-bonus pay scheme, and fixed-pay-plus-bonus pay scheme with ratchet. The social pressure manipulation involved having subordinates either personally submit their budgets and performance to a superior, or enter their budgets into a computer with no personal interaction. Moreover, internal norm and organizational commitment are measured by questionnaires built in the personal computer. The experiment was conducted by computerizing the multi-period task on the screen of man-machine interactive personal computer. To eliminate the potential social pressure, subjects in the group with no social pressure executed the computerized procedure to create a ¡¨doubled-blinded¡¨ environment where there was inter-participant anonymity (anonymity between subjects) and experimenter-participant anonymity (anonymity between experimenter and subjects), hence the effects of internal norm and organizational commitment on budgetary slack were investigated. This study tested the following hypotheses with 120 production unit managers that sampled from one manufacturing company in Kaohsiung. (1) Managers will build the least slack into their budget under a truth-inducing pay scheme, the second slack under a fixed-pay-plus-bonus pay scheme with ratchet, and the most slack under a fixed-pay-plus-bonus pay scheme. (2) Managers will build less slack into their budget as social pressure from superior is increased. (3) The difference in budgetary slack between the truth-inducing pay scheme and fixed-pay-plus-bonus pay scheme with ratchet will be reduced as social pressure from superior is increased. That is, there is an interaction between pay scheme and social pressure. (4) The level of slack built into the budget will be negatively correlated with the managers¡¦ degree of internal norm in condition of no social pressure. (5) The level of slack built into the budget will be negatively correlated with the managers¡¦ degree of organizational commitment in condition of no social pressure. The test result verified the mentioned-above hypotheses except item (1) that is partially supported. This study not only extends the management accounting literature that investigates the effects of pay schemes, but also further examines the potential effects of social pressure from superior, subordinates¡¦ internal norm and organizational commitment on budgetary slack. Especially, the results that isolated the effects of internal norm from social pressure on budgetary slack have shown the implications of personnel recruitment and managerial style in the enterprises organization.