Rural households in Tanzania are increasingly diversifying their livelihoods by shifting labor from farming to off-farm activities. However, little is known about how this shift impacts farm management. This research addresses the gap by utilizing panel data derived from the Living Standards Measurement Survey (LSMS). The study assesses the effect of off-farm work on farm technical efficiency by estimating the farm production function using a Stochastic Frontier Analysis (SFA) approach. The findings reveal that the squared term of farm-specific off-farm hours had a positive and highly significant coefficient, indicating that increased participation in off-farm work negatively impacts farm technical efficiency. These results suggest that policies aimed at improving farm productivity should account for the fact that greater involvement in off-farm work diminishes farmers' ability to effectively manage their farms