When Hailee Steinfeld was making True Grit with the Coen brothers, Jeff Bridges, and Matt Damon, the men would often talk shop, dropping actors' names and classic-movie references. Steinfeld, just 13 at the time, would go home each night and Google actors and titles. But it was overwhelming. Two summers ago, when the scenario repeated itself on the set of Begin Again (rated R, out June 27), the musical romance from Once director John Carney starring Mark Ruffalo and Keira Knightley, Steinfeld decided to be proactive. (She has a pivotal role as the daughter of Ruffalo's washed-up music exec and his estranged wife, played by Catherine Keener.) When Ruffalo and Keener were discussing a favorite film, Harold and Maude, Steinfeld surprised them by admitting she'd never seen it but would they make her a list of essential movies to watch? ''Their conversations were so intelligent and so intriguing that part of me wanted to be part of it, but I had no idea where I'd even begin,'' recalls Steinfeld, now 17. ''I was like, 'I have two of the greatest actors in the world in front of me. Why don't I ask them?'''
The assignment was perfect for Ruffalo and Keener, passionate cinephiles and Oscar nominees who'd built careers on offbeat characters and eclectic films. They began compiling a list for Steinfeld, an Oscar nominee herself. The challenge soon spiraled into obsession. ''We were thinking in particular of Hailee,'' says Keener, ''but Mark and I also talked about, 'Wouldn't it be great if we did a book for young actors or even young people interested in film of the top 100 movies they really should see?''' So at Begin Again's wrap party, the two presented their movie daughter with a bundle of Blu-rays. ''It is a master's class of great filmmaking,'' says Ruffalo, noting that the gift was ultimately limited by cost and the selection at a Manhattan Barnes & Noble. ''Some of them had great girl [roles], some of them had great women, some of them just had great relationships, like Harold and Maude, but they were mostly just really great films that were appropriate for someone her age. I said to her, 'God, I wish I had never seen Harold and Maude just so I'd get to discover that movie again.'''
The list which the actors stress is far from definitive features films from seven decades, with the 1970s best represented. (Ruffalo is a big fan of two from that decade, Paper Moon and Alice Doesn't Live Here Anymore, that sketch indelible parent-child relationships like the ones in Begin Again.) Keener admits she was mortified to discover that Ruffalo had included two of her own films, but he insisted: ''Those are quintessential modern movies with great female performances by it happens to be Catherine Keener.''
The budding cinephile says she's still working her way through the collection. The first movie she tackled: Annie Hall, which had the desired effect. ''It made me realize I love what I do so much because you're able to give that same feeling to people,'' says Steinfeld, now shooting Pitch Perfect 2. ''It's been so amazing because I find that when a conversation is happening at an event or a dinner, it trails back to these classic films.''
1. My Man Godfrey 1936
''Carole Lombard is beautiful and elegant, and I loved the way it was directed,'' says Catherine Keener. ''Not one extra beat in a movie full of tricks not fakery.''
2. The Philadelphia Story 1940
''A classic, amazing, beautiful Katharine Hepburn performance,'' says Mark Ruffalo of director George Cukor's rom-com. ''Sweet and funny, it's the perfect capsule of that time period.''
3. Sullivan's Travels 1941
''It was such a sophisticated movie for that period, with all these twists and turns and double meanings,'' says Keener. ''It was just such a surprise to me when I saw it as a kid with my dad.''
4. Dial M for Murder 1954
''This was my first film with Grace Kelly, and she's so stunningly effortless,'' says Hailee Steinfeld. ''The simplicity of her and the movie is really something else.''
5. On the Waterfront 1954
Marlon Brando is the showstopper, but Ruffalo says Eva Marie Saint is ''a study in vulnerability and presence and guilelessness for a young actress.''
6. Anatomy of a Murder 1959
''A quintessential noir film'' from genre master Otto Preminger, says Ruffalo, with Lee Remick playing the enigmatic woman whose husband is charged with the murder of her alleged rapist.
7. The 400 Blows 1959
''A beautiful performance [by young Jean-Pierre Léaud], and a powerful perspective of the world from a child's point of view,'' says Ruffalo.
8. Breathless 1960
''It's so funny when you think of the New Wave, because each filmmaker was his own wave,'' says Keener. ''I wish I knew French because Breathless is so beautiful.''
9. Breakfast at Tiffany's 1961
''Audrey Hepburn, she's heaven,'' says Steinfeld. ''It's just so iconic that once you see it, you just instantly know why everyone loves it. She's everything.''
10. Persona 1966
''Persona blew my mind. That was another shift in how I viewed movies,'' Keener says. ''Liv Ullmann was perfect, and what actress doesn't have the desire to stop talking for good?''
11. Easy Rider 1969
''It's punk rock. It's daring. It's modern,'' Ruffalo says. ''It's the first of a kind of American modernism.''
12. The Last Picture Show 1971
''It's raw and unvarnished, by one of the great American filmmakers,'' Ruffalo says of Peter Bogdanovich's black-and-white nostalgia piece.
13. Harold and Maude 1971
''Auntie Mame meets Holden Caulfield,'' says Ruffalo. ''It's just an incredibly profound love story that cracks open mortality and the ideas and definition of romantic love and pathos and teen angst.''
14. Paper Moon 1973
''I remember seeing it when I was 8 or 9 and being extremely inspired by Tatum O'Neal's performance,'' Steinfeld says. ''She was [my age], and I just remember thinking, 'If she can do it, I can do it.'''
15. Day for Night 1973
Life and art crash together in François Truffaut's series of relationship vignettes about a star-crossed movie production. ''It's filmmaking at its finest,'' Keener says.
16. Chinatown 1974
''Great career-making performances from Jack Nicholson and Faye Dunaway, with a Polish director [Roman Polanski] delivering the best of American filmmaking with a French flair,'' Ruffalo says.
17. A Woman Under the Influence 1974
A look at the trials of a housewife that director John Cassavetes wrote for his offscreen spouse, Gena Rowlands. Keener calls the film ''a beautiful husband-wife collaboration of sheer power.''
18. Alice Doesn't Live Here Anymore 1974
To Ruffalo, Martin Scorsese's film about a widow and her son was ''a total breakaway [after Mean Streets] with just amazing kids' performances,'' including Jodie Foster's supporting role.
19. Taxi Driver 1976
''Iris was so her own person, and she wasn't about to let anybody tell her what to do,'' Steinfeld says of Foster's teenage prostitute. ''It made me think how Jodie felt playing that role or how she was able to comprehend what she was doing.''
20. Grey Gardens 1976
''It's just so honest,'' says Keener. ''These are like people who we are related to the possibilities of our relations that we never quite reach. It felt like my family.''
21. Annie Hall 1977
''I pulled out a notebook after I saw it and started writing about how I loved Diane Keaton's character,'' Steinfeld says. ''My thoughts were running wild. I still have a hard time wrapping my head around it.''
22. The Last Waltz 1978
''For me, that movie was Joni Mitchell blowing everybody away,'' Keener says. ''I wanted Hailee to see that kind of raw power and talent.''
23. Being There 1979
''Amazing stylistic performance from Peter Sellers and great character work, and that's Shirley MacLaine just smashing it,'' says Ruffalo.
24. Being John Malkovich 1999
''This started for me with reading the script and going, 'Who is [screenwriter] Charlie Kaufman, and what the f--- is wrong with him?' in the most amazing way,'' Keener says. ''It kept going weirder and weirder.''
25. Best in Show 2000
Catherine O'Hara leads a cast of ''comediennes that were beautiful and sexy and funny and loose and absolutely delicious,'' marvels Ruffalo.
26. Lovely & Amazing 2002
''Keener is just so cool,'' Steinfeld says. ''She's the smartest one in the room and she just knows it. And she's so great in that film.''