[en] The extensive set of polarization data obtained at the ZGS for elastic proton-proton scattering at 6 GeV/c at a full set of values of t are used to determine the five complex reaction amplitudes, using the optimal formalism. The determination is easiest in the transversity formalism, and from that the planar amplitudes (including the helicity amplitudes) are obtained. A complete determination is made at 20 different values of t, from t = -01 to t = -1.0,l using data interpolated in t. In addition, a less complete set of data permits the determination of the five magnitudes (but not of the four phases) in the range from t = -1.0 to t = -2.0. The magnitudes of the five amplitudes can be obtained without any ambiguity, but for the four relative phases several distinct solutions exist, one of which is selected on the basis of continuity in t and minimum chi-square. There continues to be evidence that in the planar system in which the orientation axes are 90₉ from the helicity axes, all amplitudes tend to be either pure real or pure imaginary