Accurate fate models are required to assess the environmental impacts and risks associated with the release of veterinary antibiotics to soils, sediments and surface waters.  Examination of the chemical structures of veterinary antibiotics suggests that sorption to soils may occur by one, or several, mechanisms: (1) electrostatic attraction to oppositely charged sites on soil organic matter, (2) cation exchange reactions with clay minerals, and (3) surface complexation to soil and aluminum oxides.  A broad screening approach was applied to statistically assess the soil factors controlling the sorption of the high-use antibiotics, oxytetracycline and ciprofloxacin.  Thirty agricultural soils comprising 5 orders were analyzed for a wide range of characteristics (e.g., pH, texture, and exchangeable cation, oxide, and organic matter content).  Sorption kinetics and isotherms were measured on a sub-set of soils to determine appropriate equilibration times and concentration ranges for linear sorption coefficients.  Single-point soil-water sorption coefficients were measured for all soils for oxytetracycline at pH 5.5 and for ciprofloxacin at pH 5, 6, 7, and 8.  Oxytetracycline sorption at pH 5.5 was controlled by fine soil texture, high cation exchange capacity and high iron and aluminum oxide content, as determined by principle component analysis (PCA).  Ciprofloxacin sorption at all pH values was controlled by fine soil texture and cation exchange capacity, despite the decrease in mass fraction of cationic ciprofloxacin species from pH 5 to pH 8.  Multivariate regression analysis (MRA) of the sorption coefficients corroborated the PCA results; however, the low variance explained by MRA prevented the development of robust predictive models for sorption coefficients.  Results of this study indicate that the mobility and bioavailability of oxytetracycline and ciprofloxacin will be lower in clay- and oxide-rich soils and clay-rich soils, respectively.  Soil pore water pH and competing cation and ligand concentrations will also influence sorption.