Abstract: This study determines smallholder farmer’s decision to adopt of sustainable agriculture practices (SAPs) based on the assessment of profitability margin among smallholders SAPS adopters and Non adopters in Kilosa district, Morogoro. A total of 550 respondents were chosen for the study after a random sampling of the baseline dataset as a follow-up to SIMLESA adoption pathway project. Gross margin was developed using plot-level data gathered from maize farmers in Kilosa Tanzania.