A laboratory investigation was conducted to identify principal variables-initial mixing water content, porosity, and binder content- impacting undrained shear strength (qu) of stabilized sulfur-rich silty soil. An equation for predicting qu of stabilized soil was established based on the experimental data. Initially, samples were prepared with soils sample with different initial water and binder contents. Multicem, a binder consisting of a mix of cement and cement kiln dust, was added to the samples. Three different percentages of Multicem were mixed at five different soil water contents to measure qu of stabilized mixtures to understand how water content and porosity levels in the samples affect the performance of the binder and their combined impact on the strength of the samples. The soil-binder mixtures were compacted and subsequently cured in laboratory-controlled environment. The prepared samples were tested in uniaxial compression test apparatus. The results evidenced that binder content and corresponding porosity affect the strength of specimens at an equal water content. The results showed that at equal initial mixing water content, the qu of a sample increased by increasing binder content. Furthermore, it was observed that increase of binder content has a reverse effect on porosity. It was appeared lowering the soil water content, initially increased the strength until an optimum water content. Further lowering water content increased the porosity and consequently decreased qu of samples. Moreover, a ratio of porosity/volumetric binder content was chosen to evaluate the impact of these two variables on strength of samples. This study showed that qu is an exponential function of porosity/binder volumetric content ratio which depends on initial mixing water content of mixtures. It was shown at water content lower than the optimum, results of stabilization are more effective than in soil at higher water contents. Therefore, reducing the water content and thereby porosity has more significant effect on improving qu than increasing the binder content.