A collaborative experimental and theoretical study of rotationally inelastic collisions of CN (A (2)Pi, v=3, N=60-62) fine-structure Lambda -doublet levels with helium is presented. Experimental state-to-state rate constants were determined with an optical-optical double resonance technique. The CN radical was prepared by 193 nm photolysis of BrCN diluted in slowly flowing helium at a total pressure of similar to0.3 Torr. Specific levels of CN(A (2)Pi ,v=3,N=60-62) were prepared by excitation with a pulsed dye laser on various rotational lines in the A (2)Pi -X (2)Sigma (+) (3,0) band, and collisionally populated levels were probed after a short delay by laser fluorescence excitation in the B (2)Sigma (+)-A (2)Pi (3,3) band. Final state distributions (relative state-to-state rate constants) are reported. To calibrate their magnitude, absolute total removal rate constants were determined. The measured rate constants were compared with theoretical rate constants computed in a quantum scattering treatment of the dynamics based on ab initio CN(A (2)Pi)-He potential energy surfaces. The agreement of measured and computed rate constants is very good. The state-to-state rate constants display propensities for conservation of the Lambda -doublet and fine structure labels for the range of initial levels studied. The significant differences in the final state distributions in CN(A (2)Pi)-He collisions and the previously studied CN(A (2)Pi)-Ar system are shown to arise from differences in the interaction potentials for these two systems.