Diane Keaton's  greatest performance?
Where to start?
There's her Oscar-winning turn in Annie Hall .
Her portrayal of American revolutionary Louise Bryant in Reds .
Her doomed bed-hopping party girl in Looking for Mr. Goodbar .
Not to mention her recurring role as Kay Adams Corleone in the Godfather  series.
And we’re just getting started.
But I'd like to make the case that Keaton's best work – or at least the role that most perfectly dovetails with her actorish sensibilities – is that of J.C. Wiatt in 1987's Baby Boom .
Now I'm not going to tell you that Baby Boom is a great movie.
Its plot is so transparent that a hermit who spent the last 50 years alone in a cave will be able to tell you a third of the way in how it will end.
But Keaton is an absolute hoot as a cutthroat Wall Street careerist who finds herself saddled with a dead relative’s 13-month-old baby girl.
Involuntary motherhood forces J.C. out of her beloved job and into exile in small-town New England, where she gradually develops some parenting skills, falls for the hunky local veterinarian (Sam Shepard ) and eventually comes up with an idea for a homegrown business that will make her rich again.
As critic Roger Ebert has pointed out , "Baby Boom makes no effort to show us real life. It is a fantasy about mothers and babies and sweetness and love, with just enough wicked comedy to give it an edge...Like a Frank Capra  film, Baby Boom shows us a little of the darkness and a lot of the dawn."
The whole enterprise seems to have been calibrated to dovetail with Keaton's jittery screen presence, with Nancy Meyers'  screenplay exploiting both the actress's space-head sensibility (familiar from her Woody Allen  films) and the more tough, resolute persona of her dramatic roles.
Clearly, Meyers has her finger on the pulse of Keaton's on-screen persona.
Before leaving, a few appreciative words about Shepard's performance as the male love interest.
Shepard isn't a terrifically demonstrative actor; he's most effective when he remains passive and lets the audience impose their feelings on him.
Here he's the perfect embodiment of the New England male – simple, honest, handsome.
But he has some very funny moments simply by suggesting his character's amusement, amazement and finally devotion to Keaton's harried J.C.
See Bob's general introduction  to the Fool for Cinema film series.
About the Author
Robert W. Butler  is a lifelong Kansas City area resident, a graduate of Shawnee Mission East High School and the William Allen White School of Journalism at the University of Kansas. For several decades he was the movie editor of the Kansas City Star; he now writes a movie-themed blog at butlerscinemascene.com . He's married to the former Ellen Vaughan; they are the proud parents of LA-based comedian, writer, director and TV personality Blair Butler. He used to be a dog person but now lives with two cats, thus demonstrating the flexibility of the human condition.