We report a systematic study of the linear rheology of solutions of model semiflexible polymers, actin filaments (F-actin), using mechanical rheometry, diffusing wave spectroscopy (DWS), and video-based single-particle tracking microrheology. For pure actin at c = 24 mu M and after full polymerization, the elastic and loss moduli still increase with time as G＇(t) proportional to t(0.25+/-0.02) and G "(t) proportional to t(0.15+/-0.03), when measured at 1 rad/s, during network formation and reach a plateau after 12 h. At equilibrium, the linear small-frequency elastic modulus has a small magnitude, G(p)＇ = 14 +/- 3 dynes/cm(2). The magnitude of G(p)＇, depends weakly on concentration as G(p)＇(c) proportional to c(1.2+/-0.2), with an exponent much smaller than for flexible polymers. At large concentrations, F-actin network becomes a liquid crystal and G＇, is independent of concentration Using the large bandwidth of DWS, we show that; the high-frequency viscoelastic modulus of F-actin solutions varies with the shear frequency as \G*(omega)\ proportional to omega(0.78+/-0.10) for both the isotropic phase and liquid crystalline phase. These results are in good agreement with a recent model of semiflexible polymer solutions (the "curvature-stress" model) and reflect the finite rigidity of F-actin.