Technical Abstract: Testosterone is a naturally occurring endocrine disruptor (ED) that is released into the environment from natural and anthropogenic sources. The objective of this study was to achieve a better understanding of the complex fate and transport of this labile compound in undisturbed agricultural soil. This was done using batch and miscible-displacement experiments, and a comprehensive model. Degradation and transformation processes of testosterone were discerned using various batch experiments. Multiple first-order models were used to successfully describe batch experiments where simultaneous degradation and sorption processes occurred. An evolutionary global optimization strategy was used to estimate the process parameters from these batch experiments and provided high confidence in these parameter estimates. The independently determined batch parameters were then incorporated into a solute transport model and used to describe an undisturbed soil column experiment. The final modeling result was a unique identification of individual biological (e.g., degradation) and physical (e.g., sorption and transport) processes that simultaneous combined in the complex fate and transport of testosterone in soil. The estimated parameters and process model from this study were then used to simulate transport of testosterone under field conditions and provided a reasonable prediction of actual field concentrations.