Gas-phase standard state (298.15 K, 1.01325 bar [1 atm]) enthalpies of formation (Delta(f)H degrees((g))) were calculated using the atomization approach for 313 organic compounds with the Gaussian-4 (G4) composite method and for 54 molecules with the W1BD level of theory. The functional group types considered span a range of mono- and polyfunctionalized halogenated, saturated and unsaturated, cyclic and acyclic, and heteroatom (N, O, S) substituted moieties without substantial conformational complexity. Good agreement was found using both computational methods against available experimental data.