“The Glass Castle” wrestles with two conflicting impulses: the longing for order and the desire for wildness. The main object of that ambivalence is Rex Walls, a big-talking, big-dreaming ne’er-do-well played with the usual guile and gusto by Woody Harrelson.

Rex would qualify as a helicopter parent if that phrase referred to someone who encouraged his kid to pilot a chopper without proper training or safety equipment. If he and his wife, Rose Mary (Naomi Watts), don’t go quite that far, it may only be for lack of available aircraft. Their four children are, to use another slightly anachronistic idiom in reference to a story set mostly in the ’60s and ’70s, decidedly free range. At a swimming pool, Rex throws Jeannette, his second-oldest daughter, into deep water to teach her to swim. That’s hardly the craziest thing he does, but it’s a convenient metaphor for his approach to parenting.

Jeannette, played in middle childhood by a wonderfully shrewd and watchful young actress named Ella Anderson, will grow up to be played by Brie Larson and to grapple with adulthood in late-’80s New York, where she writes a gossip column. Eventually, she’ll also write a best-selling memoir of her hectic childhood, which has now been adapted into this uneven, conscientious film, directed by Destin Daniel Cretton and written by Mr. Cretton and Andrew Lanham.

Lacking the book’s episodic sprawl and psychological nuance, their movie clings to its essential tension. Jeannette, her father’s favorite — his nickname for her is Mountain Goat — admires her parents’ free-spirited individualism even as she suffers amid the chaos of their chosen way of life. Money is always short, and the family often picks up and moves, one step ahead of bill collectors or law enforcement. Rose Mary paints landscapes, still lifes and portraits, while Rex, bouncing from job to job, conjures fantastical, almost-practical projects, like the solar-powered mansion that gives the movie its title.