This work investigates the relationship between structure and dynamics for a class of “model” conjugated polymers, poly(3-alkylthiophene)s (P3ATs), and their effect on bulk physical properties. The dynamics of conjugated polymers are probed using quasi-elastic neutron scattering (QENS) techniques. QENS data probes characteristic timescales (1 ps - 10 ns) and activation energies for molecular motions corresponding to the backbone (i.e. thiophene rings) or the substitution moieties (i.e. alkyl side chains of varying length) at variable length scales (0.3-1.9 Å-1). The effect of regioregularity is also considered by comparing QENS data from regioregular and regiorandom poly(3-hexylthiophene). These motions are correlated to molecular relaxations observed through impedance spectroscopy of P3AT thick films, establishing a link between the dynamics observed from QENS and the AC conductivity of the conjugated polymer. QENS data will also be used to validate on-going molecular dynamics (MD) simulations of these systems since time and length scales are commensurate. The semi-crystalline structure of these materials is also investigated using wide-angle x-ray scattering and neutron diffraction, and key structural transitions are noted using differential scanning calorimetry (DSC). From this data, the crystalline fraction of the material is determined for use as a starting point for MD simulations. Validated simulations will help clarify the specific motions that contribute to the determination of electronic properties. The results of this work will help guide polymer chemists to rationally identify the optimal composition and placement of substitution moieties when designing new conjugated polymers. It will also help elucidate the role of molecular dynamics in the solid state with regards to the modification of electronic properties.