The homolytic bond dissociation enthalpy (BDE) quantifies the thermodynamic stabilities of product radical fragments formed by the homolysis of a covalent bond in a reactant molecule. The quantitative evaluation of BDE values provides detailed insight into the thermodynamics of bond-breaking and forming reactions, and can also be related to kinetics and selectivity by using linear free-energy relationships or empirical scaling relations. This fundamental importance has led to the use of BDE (and its free energy counterpart) values across multiple domains in chemistry, ranging from the determination of possible reaction mechanisms to computational mass spectroscopy. For example, BDE values have been used to assess the difference in bond strengths of primary, secondary, and tertiary C-H bonds, to quantify the geometric deformation necessary to reach the transition structures for Pd-catalyzed carbonhalogen insertion, for the prediction of likely molecular fragments observed in the mass spectra of short peptides , breakdown of large biomass such as lignin , comparing the stability of organic radicals and design of de novo radicals for organic redox flow batteries. Due to the broad utility and applicability of BDE values, significant effort has been invested in obtaining quantitative measurements. Experimental techniques such as pyrolysis , radical kinetics photoionization mass spectrometry, acidity/electron affinity cycles, and electrochemistry have been used to obtain BDE measurements. Besides experimental measurements, quantum-mechanical (QM) calculations have become pivotal in assessing and predicting BDE values. Emerging computational methods for the automated enumeration and exploration of reaction mechanisms use estimated BDE values to identify energetically favorable paths among the numerous possibilities. High levels of accuracy are attainable with composite ab initio computations of BDEs at 0 K (D0). For example, the CBS-QB3 method yields mean absolute errors (MAEs) of 0.58 kcal mol -l relative to experimental values for small molecules such as diatomics, hydrocarbons, and hydrides of N, S, Be, Li, and Si. However, density functional theory (DFT) calculations are often more practical for larger, conformationally flexible compounds and have been increasingly used to compute BDEs: the M06-2X hybrid meta-GGA functional gives an MAE of 2.1 kcal mol -1 relative to experimental hydrocarbon BDE measurements. Compared to experimental measurements, which typically give information about the weakest bond(s) in a molecule, computations can be used to study all possible homolytic dissociations. However, due to the exponential scaling of electronic structure calculations with the number of basis functions (and hence molecular size), performing quantum chemical predictions for larger molecules or sizable datasets is challenging, if not intractable.