The Summer I Turned Pretty trilogy shows the transition from childhood into young adulthood into adulthood. In the first book, Belly is more cognizant of what her elders, especially Susannah, want from her. However, as the trilogy progresses, she deals with bigger and more life-altering situations, such as breaking up with Conrad, Susannah's death due to cancer, Jeremiah's betrayal, and ultimately marrying Conrad. The novels illustrate the progression from child to adult through the experiences that both Belly and the Fisher boys encounter as they grow.