A study was performed to examine the aging behaviors of Al-2.1Li-2.9Cu alloy by differential scanning calorimetry and transmission electron microscopy. DSC measurements were conducted over the temperature range of $25{sim}550^{circ}C$ at a heating rate of $5^{circ}C$/min. for the specimens aged at 130, 160, $190^{circ}C$ and $220^{circ}C$ for various times after solution treatment at $540^{circ}C$ for 30 minutes. The peaks due to the formation of G.P.zone were not detected in the specimens aged at 130 and $160^{circ}C$, but those at 190 and $220^{circ}C$ appeared in DSC curves. The heat absorption due to the dissolution of ${delta}^{prime}$ phase was increased with increasing aging time at $130^{circ}C$ aging. In contrast, those values for the specimens aged at 160 and $190^{circ}C$ were initially increased and inversely decreased at the transition time of 72 and 1 hour, respectively. The heat evolution due to the formation of $T_1$ phase was nearly unchanged at $130^{circ}C$ aging, but at $160^{circ}C$ and $190^{circ}C$ aging, drastically decreased after the transition time. It can be considered that the increase of $T_1$ phase results in the decrease of ${delta}^{prime}$ phase when aging time is longer than the transition time. The hardness of the specimen aged at $190^{circ}C$ is initially higher compared with that at $160^{circ}C$, however, the peak hardness shows the lower value than that at $160^{circ}C$.