The spin-orbit selectivity of angle-resolved photoelectron spectra was used to provide new information on the electronic structure, symmetry, and decay dynamics of members of the autoionizing Tanaka-Ogawa Rydberg series in CO2. This represents the first time that spin-orbit selectivity has been used to obtain such information for a polyatomic molecule. The spin-orbit photoelectron branching ratios were used to show that the angular momentum quantum number lambda of the excited Rydberg electron does not change upon autoionization. Furthermore, a consideration of the present results together with previous calculations of the relative intensities of the discrete and continuum ionization channels shows that the most probable electron configuration for the Tanaka-Ogawa Rydberg series is...(pi(u))(3)(pi(g))(4)nd delta(g) and that autoionization proceeds primarily via a d delta g-->epsilon f delta(u), process for the totally symmetric vibronic components of the ion. The asymmetry parameter beta was determined for individual spin-orbit components of the various vibronic bands of the (X) over tilde (2) Pi(g) state and is discussed in terms of recent theoretical calculations. The Rydberg series appears to be well described by Omega(c) omega coupling, even for relatively low principal quantum numbers. The general utility of this technique for autoionizing Rydberg states and its extension to multiphoton ionization of Rydberg states that lie below the first ionization threshold are discussed.