Although an unseen character, her role is important: at the beginning of the play, Romeo's unrequited love for Rosaline leads him to try to catch a glimpse of her at a gathering hosted by the Capulets, during which he spots Juliet and falls in love at first sight with her, leading to all subsequent events in the story.

Subsequent works based on the play have experimented with making Rosaline a more prominent character; notably, the 1999 play After Juliet by Robert Nathan, the 2012 novel When You Were Mine by Rebecca Serle, its 2022 film adaptation Rosaline, and the 2017 television series Still Star-Crossed all feature her as main character.

"[4] This is the source of his depression, and he makes his friends unhappy; Mercutio comments: "That same pale, hard-hearted wench, that Rosaline, torments him so that he will sure run mad.

"[5] Benvolio urges Romeo to sneak into a Capulet gathering where, he claims, Rosaline will be perceived like "a crow" alongside the other beautiful women.

"[7] Because their relationship is sudden and secret, Romeo's friends and Friar Laurence continue to speak of his affection for Rosaline throughout much of the play.

Rosaline is a variant of Rosalind,[9] a name of Old French origin: (hros = "horse", lind = "soft, tender").

These similarities have led Charles and Mary Clarke to wonder whether they are based on a woman Shakespeare actually knew, possibly the Dark Lady described in his sonnets, but there is no strong evidence of this connection.

[13] Analysts note that Rosaline acts as a plot device, by motivating Romeo to sneak into the Capulet party where he will meet Juliet.

[14] Rosaline thus acts as the impetus to bring the "star-cross'd lovers" to their deaths—she is crucial in shaping their fate (a common theme of the play).

[15] "Rosaline and Paris...are the subtlest reflectors of all...they are cast like a snake's skin by the more robust reality of Romeo and Juliet."

Before meeting Rosaline, Romeo despises all Capulets, but afterwards looks upon them more favorably; he experiences the dual feelings of hate and love in the one relationship.

[20] In the 1750s, actor and theatre director David Garrick also eliminated references to Rosaline from his performances, as many saw Romeo's quick replacement of her as immoral.

In a brief non-Shakespearean scene, Rosaline (Dagmar Josipovitch) gives Romeo a mask at Capulet's celebration, and urges him to leave disguised before harm comes to him.

Robert Nathan's 1966 romantic comedy, Juliet in Mantua, presents Rosaline as a fully developed character.

After they are forgiven and return to Verona, they learn that Rosaline is now married to Count Paris, and both couples must confront their disillusionment with their marriages.

Another play, After Juliet, written by Scottish playwright Sharman Macdonald, tells the story of Rosaline after Romeo dies.