The $\ensuremath{\gamma}$-ray spectrum resulting from thermal-neutron capture in ${\mathrm{Te}}^{123}$ was investigated with the Argonne 7.7-m bent-crystal spectrometer. The observed spectrum consisted of 75 $\ensuremath{\gamma}$ rays with energies between 100 keV and 1.1 MeV. The spectrometer used a new split-source technique which allowed simultaneous measurement of the ${\mathrm{Te}}^{123}(n, \ensuremath{\gamma}){\mathrm{Te}}^{124}$ spectrum from capturing samples with two different isotopic enrichments of ${\mathrm{Te}}^{123}$ and thus gave immediate isotopic identification for the ($n, \ensuremath{\gamma}$) spectrum. The ${\mathrm{Te}}^{123}(n, \ensuremath{\gamma}){\mathrm{Te}}^{124}$ spectrum was also measured with Ge(Li) detectors in the energy regions 0.5-4.0 MeV (112 lines) and 5.5-9.5 MeV (63 lines) by use of the Argonne in-pile facility. The associated spectrometer has a long, split NaI ring which surrounds a Ge(Li) detector and was used to enhance the full-energy spectrum (anticoincidence) and the double-escape spectrum (coincidence). The above thermal-neutron-capture spectrum was combined with the results of an average-resonance-capture spectrum taken with the same Ge(Li) facility but with the target surrounded with boron. These ($n, \ensuremath{\gamma}$) experiments were then combined with all previous work to develop and extend the level scheme of ${\mathrm{Te}}^{124}$ and to define many of the details of the $\ensuremath{\gamma}$ decay of these levels. The new values for the first 15 level energies (keV) and ${J}^{\ensuremath{\pi}}$ are ground state, ${0}^{+}$; 602.42\ifmmode\pm\else\textpm\fi{}0.02, ${2}^{+}$; 1247.99\ifmmode\pm\else\textpm\fi{}0.05, ${4}^{+}$; 1324.82\ifmmode\pm\else\textpm\fi{}0.05, ${2}^{+}$; (1655.9\ifmmode\pm\else\textpm\fi{}0.2, ${0}^{+}$); (1736.5\ifmmode\pm\else\textpm\fi{}0.3); (1747.40\ifmmode\pm\else\textpm\fi{}0.16); 1956.18\ifmmode\pm\else\textpm\fi{}0.11, ${3}^{\ifmmode\pm\else\textpm\fi{}}$, ${4}^{+}$; 2037.68\ifmmode\pm\else\textpm\fi{}0.07, ${2}^{+}$; 2090.65\ifmmode\pm\else\textpm\fi{}0.35, ${0}^{+}$, ${2}^{+}$; 2152.04\ifmmode\pm\else\textpm\fi{}0.15, ${0}^{+}$, ${2}^{+}$; 2181.20\ifmmode\pm\else\textpm\fi{}0.40, 1, 2; 2293.10\ifmmode\pm\else\textpm\fi{}0.30, ${3}^{\ensuremath{-}}$; 2322.57\ifmmode\pm\else\textpm\fi{}0.20, ${0}^{+}$, ${2}^{+}$; 2452.9\ifmmode\pm\else\textpm\fi{}2.6, ${0}^{+}$, ${2}^{+}$. The parentheses indicate uncertainty in the level assignments, while the italic numerals indicate new spin and parity values. The relative intensities of $\ensuremath{\gamma}$ rays from states at \ensuremath{\sim}2 MeV suggest that $E2$ transitions to the two-phonon states at 1248 and 1325 keV are enhanced relative to transitions to states at 0 and 602 keV; so these 2-MeV levels are very likely collective and possibly vibrational. The ($n, \ensuremath{\gamma}$) data imply a neutron binding energy ${E}_{n}=9425\ifmmode\pm\else\textpm\fi{}2$keV for ${\mathrm{Te}}^{124}$.