Abstract: This study investigated the influence of Community involvement on the performance of water and sewerage projects in Kiambu Town in Kenya. The study was guided by the Theory of Reasoned Action. Given that this study focused on a single project—the Construction of Kiambu Water Supply and Sewerage Project—it adopted a descriptive research design and a mixed method approach. Data were collected from 338 respondents drawn from community households, funding and government officials, and M&E officers using simple random and purposive sampling. Quantitative data were analyzed statistically with the help of SPSS 25, including descriptive statistics and simple linear regression, while qualitative data were processed using NVivo 14. The study revealed that there was a positive and strong correlation between community involvement and Performance of Water and Sewerage Projects (r = 0.763, p < 0.000). The study suggests that stakeholders enhance project performance and sustainability in water and sewerage projects in Kiambu Town by strengthening community engagement and prioritizing and enhancing participatory capacity-building initiatives 

Key words: Community Involvement, Performance, Water and Sewerage Projects