Magnetic properties of a doped linear polyarylamine (PA2), whose chain includes alternating para-phenylene and meta-phenylene groups, and of two cyclic and linear model compounds (C2 and D2) were explored by pulsed-EPR nutation spectroscopy, SQUID magnetometry and DFT calculations. Stoichiometrically doped PA2 samples exhibit a pure S = 1 state (exchange coupling constant J = 18 K) with a high spin concentration (0.65) corresponding to 65% of mers bearing holes. Such properties were already observed for doped reticulated polyarylamines but are quite unusual for doped linear polyarylamines. In order to better understand the properties of PA2, model compounds C2 and D2 were also investigated: pure S = 1 spin states could also be obtained, but with higher J (respectively 57 K and 35 K) and, surprisingly, with high but still limited spin concentrations (respectively 0.77 and 0.65).