The theory of tho sp:ead of turbulent jete, based upon Chou's improved general theory of turbulenio, is civen in the presen: paper. Starting trom the differential equatious for mean motion and the equations of donble correlations for both velodity and tomperature fluctuations,the anthor hes caleulatod the moan yeloeity and the moan temperature distributions in tha two-dimensional, in the axially symmetrical and in the half jot. in all three cases the samo procedure of approximation haa been Yellowed. The results aro compared with experimental data, and the agreement Uetween theory anil experiment is quite good.