Act One

Jerusha Abbott is "The Oldest Orphan in the John Grier Home". On the day that the Trustees come to visit, she is summoned to the office for an interview with Mrs. Lippett, the Principal. On her way there, she glimpses one of the Trustees leaving the school, or rather she sees his shadow, cast by the headlights of his waiting car – a long, spindly, spidery shadow she will never forget.

Mrs. Lippett hands her a letter. It is from the Trustee she has just seen leaving the home. Impressed by her amusing satirical essays about life at the orphanage, he has devised a detailed plan for her further education. He is sending her to college with all expenses paid, with the intention that she educate herself to become a writer. Her only duty will be to write him a letter once a month describing her progress and her impressions of the college. He is so reclusive and allergic to gratitude, he doesn't even want her to know his name, calling himself Mr. Smith.  "Who Is This Man?" Jerusha wonders.

Having arrived at college, Jerusha writes her first letter. She can’t bear the thought of addressing him as Mr. Smith, so she tries out some other possibilities in "Mr. Girl Hater" before deciding to call him Daddy Long Legs.

In his study in Manhattan, the young philanthropist Jervis Pendleton is amused by Jerusha’s letter but  puzzled too ("She Thinks I’m Old").

In her next letter, Jerusha describes her anxiety at not being able to fit in to college life. She can't bear the thought of anyone knowing that she comes from an orphanage. She wants to be "Like Other Girls" and struggles to catch up with her classmates because of the "Things I Didn't Know".

In the Christmas vacation, Jerusha is left alone at college, where she devotes herself to catching up on her reading. In her loneliness she sends love to her Daddy Long Legs. The shy and awkward Jervis is disturbed by her use of the word and wonders "What Does She Mean By Love?".

Jerusha flunks two of her first exams and is mortified by her failure. She becomes ill and is confined to the infirmary from where she writes angrily to Mr. Smith accusing him of not caring for her and supporting her merely out of a sense of charity.  Moved by her plight, Jervis sends her a bouquet of flowers. Deeply affected by this gesture, Jerusha is penitent ("I’m A Beast").

Enthralled by her letters but cautious about revealing his true identity, Jervis decides to pay a visit on Jerusha, his pretext being a visit to his niece Julia, who is also Jerusha’s least favourite friend ("When Shall We Meet?"). Jerusha is fascinated by the eccentric young Jervis but becomes more and more curious about the true identity of the man she thinks of as her old, grandfatherly Daddy Long Legs ("The Color Of Your Eyes").

Summer vacation arrives and Jerusha has nowhere to go. She begs Mr. Smith to save her from having to return to the orphanage as Mrs. Lippett’s drudge. Through an imaginary ‘secretary’ to ‘Mr. Smith’, Jervis sends her instead to Lockwillow, a beautiful hillside farm, where Jerusha starts to explore her talent as a writer and feels she has discovered "The Secret of Happiness".  She also stumbles on a connection between Jervis Pendelton and Lockwillow Farm but fails to make the connection with her Daddy Long Legs.

Act Two

Back in college for her Sophomore year, Jerusha continues with her studies and her novel writing and becomes increasingly socially involved with the family of her close friend Sallie McBride. Stung by her apparent attachment to Sallie’s attractive brother Jimmy, Jervis starts to realise that he is falling for Jerusha himself. He invites Jerusha, Julia and Sallie to New York for a long cultural weekend ("My Manhattan").

Summer vacation comes round again and Jerusha asks to be allowed to stay with the McBrides at their country home. In an irrational fit of jealousy, Jervis uses his secretarial alias to instruct her to return for another summer at Lockwillow.

Feeling trapped, lonely and bored, Jerusha finds it hard to forgive Mr. Smith for his silence and lack of heart ("I Couldn't know Someone Less").

Jervis continues to agonize about his deception of Jerusha but can now see no way out of his web of lies, thinking that if he confesses his true identity, Jerusha will now never forgive him ("The Man I’ll Never Be").  Instead he visits Jerusha in Lockwillow, the farm he grew up in as a boy, where they tramp through the countryside together and are both surprised to find themselves growing more and more attached to each other ("The Secret of Happiness - Reprise").

After four years of study and several failed attempts at a first novel, Jerusha completes her studies.  She begs Daddy Long Legs to attend her graduation ceremony so she can finally meet the man who has changed her life. Jervis does attend the ceremony, ostensibly in support of his niece Julia, but cannot declare himself to Jerusha as her Daddy Long Legs. They both find themselves fighting back the tears on "Graduation Day".

Back in his study, a deeply disturbed and lonely Jervis ponders the meaning and effect of "Charity" on both the giver and receiver and how his life has been turned upside down by the young woman he has supported. At the same time, in Lockwillow, Jerusha swears she will never think of her Daddy Long Legs again ("I Have Torn You From My Heart").

A few months later, Jerusha writes to Mr. Smith to tell him she has finally had her novel accepted by a publisher. She encloses a cheque for $1000 as a first re-payment of her college fees. Overwhlemed by this gesture, and feeling a new equality between them, Jervis visits Jerusha in Lockwillow and asks her to marry him. Unable to tell Jervis of her humble origins, Jerusha feels she has to turn him down because of the huge difference in their social origins.  She writes to Daddy Long Legs one last time, declaring her love for Jervis, and appealing for a personal meeting with the man she believes is her only true friend.  Jervis writes back as Daddy Long Legs agreeing to meet her. 

Shocked and aggrieved but ultimately delighted to discover that Jervis and Daddy Long Legs are one and the same, Jerusha finally understands what has been happening "All This Time".