In today's digital era, the application of computers and related technologies in the accounting function amongst business organizations has increased, giving rise to substantial scholarly and practical debates on the subject of computerized accounting systems. Several studies have, therefore, been conducted on computerized accounting systems or accounting information systems in recent times. However, existing studies are focused on the adoption, usage, and benefits of the systems. No extant studies has attempted to explore the structural components or subsystems of computerized accounting systems and how these components contribute to the overall performance of the systems. To fill this gap, the present study has attempted to explore the contributory impact of the structural components (subsystems) of computerized accounting systems to the systems' overall performance. This study, therefore, decomposed computerized accounting systems into five components and, employing structural equation model (SEM), sought to determine the contributory impact of each of the components to the holistic performance and effectiveness of the systems, with a focus on small and medium enterprises in Nigeria. The quasi-experimental, cross-sectional survey was employed in the study and questionnaires were administered to 370 firms that were selected using the stratified random sampling technique. The results of the study indicates that all five components, individually, made significant contribution to the overall performance of computerized accounting systems (CAS). The study, therefore, concluded that each of the structural components of CAS, namely internal controls, automated data-processing, relational database, automated reporting, and enhancing technologies, individually, contributed significantly to the overall performance of the systems. Hence, all the five components are necessary in the design, modelling, choice, and adoption of computerized accounting systems for SMEs. The study is significant as it contributes empirically to the body of knowledge in the subject. Options for further research are also suggested for the validation and, or, extension of the study's results.