Despite expectations that system integration projects for utilizing mobile systems in enterprises will rapidly proliferate both domestically and internationally, existing research on the acceptance and utilization effects of mobile systems remains limited both in Korea and abroad. This study sought to examine the organizational adoption process of PDA systems, a representative mobile device, and to investigate the factors influencing their acceptance. In particular, this study aimed to compare the phenomena observed in prior research on voluntary technology acceptance with those of involuntary technology acceptance. According to the research results, the findings for the research variables used in prior technology acceptance studies were generally similar to those of previous studies, with the exception of result demonstrability. Specifically, the results regarding self-efficacy and enjoyment were consistent with prior research findings for both the voluntary and involuntary user groups. Furthermore, high professional fit was found to enhance the perceived usefulness of the system for both PDA user groups. However, the results of this study demonstrate that the characteristics of mobile systems may lead to differential perceptions of system usefulness and ease of use depending on the degree of user voluntariness. User training had an overall positive effect on perceived ease of use, though the results were more significant for the involuntary user group. Additionally, contrary to expectations, technical support was found to have a negative effect on ease of use, with particularly serious implications for the voluntary user group.