In-house software development is a critical phenomenon for the production of efficient and effective software in generating requisite job output. A few studies have devoted efforts towards establishing the impact of in-house software development on software. Therefore, this paper is an effort towards establishing the impact of in-house software development practices on system usability. In pursuit of this paper, a sample of a sample size of 169, at 95% confidence level, with margin error of 5% was drawn from bold software users, i.e. 300 employees who used the all software including those dealing with the main stream activities. A total of 102 respondents actually responded to the questionnaires. The Online Sample Calculator was used to draw the sample. Quantitative data were collected using semi-structured questionnaires and processed using the SPSS. Descriptive statistics were applied in the analysis. Findings of the study indicate that software development practices, specifically usability test and user involvement in software designing and development had an impact on determining software usability for in-house software. The paper concludes that software development practices shape the design of the software; hence influence usability of the software produced. Recommended is therefore that software usability test and user involvement in software designing and development be promoted for effective software production.