Entropy scaling is an intriguingly simple approach for correlating and predicting transport properties of real substances and mixtures. It is convincingly documented in the literature that entropy scaling is indeed a firm concept for the shear viscosity of real substances, including hydrogen bonding species and strongly nonspherical species. We investigate whether entropy scaling is applicable for thermal conductivity. It is shown that the dimensionless thermal conductivity (thermal conductivity divided by a reference thermal conductivity) does not show a single-variable dependence on residual entropy, for obvious choices of a reference thermal conductivity. We perform a detailed analysis of experimental data and propose a reference thermal conductivity that is itself a simple function of the residual entropy. We then obtain good scaling behavior for the entire fluid region for water and 147 organic substances from various chemical families: linear and branched alkanes, alkenes, aldehydes, aromatics, ethers, esters, ketones, alcohols, and acids. The residual entropy is calculated from the Perturbed Chain Polar Statistical Associating Fluid Theory equation of state. The correlation of experimental data requires two parameters for pure substances with scarce experimental data and up to five parameters for experimentally well-characterized species. The correlation results for all substances lead to average relative deviations of 4.2% to experimental data. To further assess the approach, we analyze extrapolations to states not covered by experimental data and find very satisfying results.