en Psychology Psychology Original Research Original Research <strong>Background: </strong>Procrastination is a common and widespread phenomenon that affects 15-20% of the general population and 50% of students. Since developing and providing beneficial and effective interventions for procrastination needs a strong, comprehensive theoretical background explanation, the aim of the study was to assess the underlying transdiagnostic factors of procrastination and presenting a causal model.<br> &nbsp;&nbsp; <strong>Methods:</strong> In this cross-sectional study, 390 college students were asked to fill out a packet of self-report measures, which included the Pure procrastination scale, Difficulties in emotion regulation scale, Depression-anxiety-stress scales, Frost multidimensional perfectionism scale, Rumination response scale, Penn state worry questionnaire, Acceptance and action questionnaire. The causal model was tested using structural equation modeling (SEM).<br> &nbsp;&nbsp; <strong>Results:</strong> Results of the SEM indicate that perfectionism was significantly associated with increasing emotion dysregulation (&beta;=0.446, P<0.001) and emotion dysregulation was significantly associated with increasing anxiety (&beta;=0.499, P<0.001) and depression (&beta;=0.478, P<0.001), and then anxiety and depression with other variables, such as worry (&beta;=0.245, P<0.001; &beta;=0.004, P=0.935), rumination (&beta;=0.046, P=0.424; &beta;=0.418, P<0.001) and experiential avoidance (&beta;=0.277, P<0.001; &beta;=0.319, P<0.001) related to procrastination. Finally, worry has the most significant increasing effect on procrastination. The very small root mean square error of approximation (RMSEA=0.038), together with large values of comparative fit index (CFI=0.985), relative fit index (RFI=0.917), and normed fit index (NFI=0.979) indicated that the model was well fit.<br> &nbsp;&nbsp; <strong>Conclusion:</strong> Perfectionism, emotion dysregulation, negative affects, worry, rumination, and experiential avoidance, known as transdiagnostic factors, had a causal relationship with procrastination, and reducing each transdiagnostic factor will improve procrastination. This study could be considered as a cornerstone for further studies on procrastination from a transdiagnostic approach. Procrastination, Emotion Dysregulation, Transdiagnostic Factors, Structural Equation Modeling 899 905 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-6635-1&slc_lang=en&sid=1 Leili Jamil Leili.jamil1989@gmail.com 200319475328460065158 200319475328460065158 No Department of Clinical Psychology, AJA University of Medical Sciences, Tehran, Iran Ahmad Ashouri ahmad.ashouri@gmail.com 200319475328460065159 200319475328460065159 No Department of Clinical Psychology, School of Behavioral Sciences and Mental Health, Tehran Institute of Psychiatry, Iran University of Medical Sciences, Tehran, Iran Somayeh Zamirinejad zamirinejad.s@iums.ac.ir 200319475328460065160 200319475328460065160 Yes Department of Clinical Psychology, School of Behavioral Sciences and Mental Health, Tehran Institute of Psychiatry, & International Campus, Iran University of Medical Sciences, Tehran, Iran Behzad Mahaki behzad.mahaki@kums.ac.ir 200319475328460065161 200319475328460065161 No Department of Biostatistics, & Social Development & Health Promotion Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran