The main purpose of current study was to predict work efforts and organizational citizenship behaviors through multi-dimensions of work motivation (including, amotivation, social extrinsic, material extrinsic, introjected, identified, and intrinsic motivations). This study was a descriptive-correlational method, and the study population included all of the employees in Welfare Organization in Isfahan province. 285 employees were selected through convenience sampling method. Research instruments consisted of 5-item scale of Work Efforts by Kuvaas, et al., 19-item scale of Multi-Dimensions Work Motivation by Gagne, et al., and the 16-item of Organizational Citizenship Behaviors by Lee and Allen. The data were analyzed using Pearson correlation and multiple regression analyses. The findings demonstrated that there were negative relationship between amotivation and material extrinsic motivation and positive relationships of intrinsic, identified and introjected motivations with work efforts. There were negative relationship between amotivation and positive relationships of material extrinsic, identified, introjected and intrinsic motivations with organizational citizenship behaviors (p<0.01). Moreover, amotivation, material extrinsic and intrinsic motivations predicted work efforts significantly (p<0.01), and amotivation, social extrinsic and intrinsic motivations predicted organizational citizenship behaviors significantly (p < 0.01), which explained 15.8 and 26.2 percent of the variances of work effort and organizational citizenship behaviors respectively. Based on the results of this study it can be concluded that the work effort and organizational citizenship behaviors could be increased by work motivation.