<p>Understanding charge transport in amorphous organic materials is crucial for improving organic electronic devices such as OLEDs and solar cells. We employ first-principles calculations to describe charge transport mechanisms in an amorphous polymer melt. Charge carriers in organic systems are polarons, which are dielectrically stabilized by the surrounding media. Polarons move along and between chains in a disordered melt, in which dihedral disorder imposes a barrier to polaron motion along the chains, while polaron hopping between chains is described by Marcus theory. To implement this scheme, we extend our previous tight-binding model, validated for excitons. The barriers are heterogeneous; transport is governed by a characteristic length and time for a carrier to move along and hop between chains. We predict charge mobility in amorphous poly(3-hexylthiophene) [P3HT] melt, with configurations taken from well-equilibrated molecular dynamics simulations. We find good agreement with mobility experiments without adjusting any parameters. Our approach provides insight into charge transport in amorphous organic semiconductors, potentially guiding the design of more efficient organic electronic devices.</p>