Several themes run through the stories in Olive Kitteridge. In fact, in addition to the presence of Olive in each story, and the setting, it is the recurrent themes that unify the stories into a coherent whole. The first theme, appropriately enough, is a resonance or echoing among people. When one character is going through something and feels desperately alone as a result of how hard it is, another character across town, or perhaps half a dozen of them, experiences the same event or emotion. This happens on the level of plot and character interaction, as when Olive and Kevin both have a parent who committed suicide in "Incoming Tide." It also happens, however, on less literal levels. In "Starving," young Nina White literally starves herself to death through her anorexia, but Harmon, whose observations of Nina start the story in motion, is hungry for love. So too are his girlfriend Daisy Foster and Olive, who wanders into the story almost by chance.

One of the reasons characters resonate with one another so much is that they are all facing the same emotional challenge: how hard it is to love, and yet how important it is. In these stories, author Elizabeth Strout explores every sort of love one can imagine—and every sort of difficulty one can face when loving. There is casual sex that grows into love (between Harmon and Daisy Foster, in "Starving"). There are illicit affairs, like the one Bob Houlton has in "Winter Concert" or Angie O'Meara has in "Piano Player." There are failed and successful marriages aplenty, boyfriends and girlfriends, and all arrangements in between, including actual love between parents and children, attempts at love between parents and stepchildren, and surrogate love between unrelated members of different generations. The characters face challenges ranging from death (as when Denise Thibodeau's husband is shot) to the emotional residue of suicide (for both main characters in "Incoming Tide") and on to the lingering weight of having a husband institutionalized due to a stroke (as Olive must deal with throughout several of the book's later stories). Love is essential for these stories, but it never flows easily.

Another reason the characters so often resonate is that ultimately the world of Olive Kitteridge is a world of symbolic serendipity. That is to say, throughout the collection, people encounter things, events, and other people at just the right time to spark realizations, emotional exposure, and growth. For example, Olive Kitteridge just happens to drop by Daisy Foster's when asking for money, and just happens to do so at a time when Harmon is there, and at a time when Nina, an anorexic, is trying to eat a doughnut. This gives Olive a chance to share comments on how everyone is starving emotionally, which in turn leads Harmon to realize his desire for Daisy is love, not just lust. Seasons, special events, chance encounters, and even the tides align to force characters to grow in Olive Kitteridge, creating a world in which everything is meaningful and where drama happens as much internally as externally.