During childhood, episodic memory demonstrates marked improvements that are supported by the protracted development of the hippocampus and a larger network of cortical regions. To date, most research has focused on associations with the hippocampus in this age group. Few studies have explored the contribution of cortical regions and no studies have explored this longitudinally. Thus, the first aim of this dissertation was to examine the longitudinal co-development of cortical thickness and surface area in memory-related cortical regions with a latent episodic memory variable in 4- to 8-year-old children (N = 177). Findings, uncorrected for multiple comparisons, demonstrated that a thinner cortex in multiple episodic memory network regions (i.e., inferior frontal gyrus, inferior parietal sulcus, lingual gyrus, middle temporal gyrus, precuneus, lateral occipital cortex, superior frontal gyrus, superior parietal lobule, superior temporal gyrus, and temporal pole) at age 4 predicted more rapid improvements in memory performance from age 4 to 6 years. Similarly, greater surface area in the precuneus and less surface area in the medial orbitofrontal gyrus at age 4 also predicted more rapid improvements in memory performance from age 4 to 6 years. Additionally, results revealed that several regions demonstrate parallel co-development with latent episodic memory performance from age 4 to 8 years. Specifically, greater changes in cortical thickness and surface area of the entorhinal cortex were associated with greater changes in memory from age 4 to 6 years. Furthermore, cortical thickness of entorhinal cortex and surface area of anterior cingulate cortex, entorhinal cortex, inferior parietal sulcus, lingual gyrus, and superior temporal gyrus showed co-development with latent episodic memory from age 6 to 8 years. Together, these findings suggest that cortical thickness and surface area of the episodic memory network support improvements in memory performance during childhood. However, these findings did not survive correction for multiple comparisons. Although age-related differences were one focus of this investigation, individual differences were another. Specifically, during childhood children transition away from afternoon napping. This transition has previously been associated with differences in memory consolidation abilities and hippocampal maturation. These associations suggest that habitual nappers require more regular sleep to consolidate memories due to an immature episodic memory network. However, limited work has examined these associations outside the hippocampus. Therefore, the second aim of this dissertation was to examine whether regions that support longitudinal memory development differ as a function of nap habituality (N = 44). Findings revealed significant differences in cortical thickness of right inferior frontal gyrus and surface area of lateral occipital cortex, such that non-nappers demonstrated a thinner cortex and greater surface area in these regions compared to nappers, though these findings did not survive correction for multiple comparisons. Thus, although there is some evidence that memory-related cortical regions may differ based on nap habituality, additional work is needed to support this claim. Together this dissertation provides new data on the co-development of memory with brain structure in the episodic memory network and identifies individual differences that may be associated with these brain structures.