Cost overrun or schedule delay of the software development project happens frequently despite that software developers continue to make every effort for the effective management of the projects. Previous researches have ascertained that these problems are ascribed to the uncertainty of projects and the improper management of the projects. The purposes of this research are to investigate the impacts of user participation and task interdependence on the performance of the projects and also to find out the appropriate project management method to improve the project performance. Even though the model fitness of the path model is proved to be very high, the verification of the hypotheses showed a variety of results including the four verifications and the one refutation of the hypotheses as well as the suggestion of one alternative hypothesis. The contribution of this research is that the integration model is proposed and verified, comprising the relationship among the user participation, the task interdependence, and the performance of software development projects. A project manager can utilize the implication of this research for an effective management of software development project.