Previous research conducted at the University of Alberta has revealed that addition of phosphogypsum (PG) to a mixture of tailings cyclone underflow and mature fine tailings produces a nonsegregating tailings stream known as composite tailings (CT). The objective of the laboratory testing program was to increase the understanding of the chemical and physical processes which influence the dewatering characteristics of CT. A complete set of equations for defining the compositional characteristics of CT were developed. The results of the testing program showed that CT placed in 5 cm high deposits experiences an immediate downward movement and undergoes hindered sedimentation followed by self-weight consolidation. Increasing the PG dosage up to 3200 g/m 3 results in an increase in the mass of release water and the presence of an optimum dosage was not observed. CT has a compression index consistent the upper limit of with pure kaolinite and hydraulic conductivity which spans two orders of magnitude.