Author Anne Lamott, 57, planned to be a grandma sometime around the ripe age of 65.

So when it happened in 2009 that her son, Sam, now 22, and his girlfriend, Amy, now 23, announced they were having a baby, Lamott first greeted the news with silence.

"It was unexpected. My son was very young and his girlfriend was very young," said Lamott by phone a few days before a visit to Atlanta. "It would not have been my first choice but as I say in the book, who asked me? It was about learning, as usual, to let go, let go, let go of the control ... and some days go better than others."

As she did for the 1993 bestseller about her son's first year of life, Lamott put fingers to keyboard, charting the course of her grandson's first year (with an assist from Sam) in "Some Assembly Required: A Journal of My Son's First Son" (Riverhead Books, $27). But where Lamott was once writing about the chaotic demands of single-parenting, she now writes about scheming to get more time with her grandson ... and the constant struggle to stay out of Amy and Sam's business.

"Motherhood has been the great teacher in teaching me what you can and cannot do in terms of changing people or the outcome," Lamott said. "Motherhood taught me whatever patience I have and grandmotherhood just reinforces all those things."

As she notes in the book, her exercises in patience began almost from the start. Lamott had promised to pay her son's bills throughout his four-year education at a pricey art academy in their hometown of San Francisco. Now, with baby Jax and Amy moving into Sam's studio apartment, those costs were sure to skyrocket. When Sam and Amy's sometimes tumultuous relationship spilled over into Lamott's life, she learned to hold her peace.

"It is practice, practice, practice. You practice letting go and not saying anything unless you are asked. There is an acronym, WAIT. That stands for ‘Why Am I Talking' and I have learned to really hold my tongue a lot," Lamott said.

Her efforts came in handy when, for instance, Amy bought a one-way ticket to North Carolina, threatening to take Jax to live with her parents. Lamott suffered greatly at the thought of being separated from her newborn grandson.

"I have been so lucky to have these years with him. I know him on an almost day-to-day basis. I know him in a casual and intimate way," said Lamott. Amy ultimately decided to make the trip a vacation instead of a permanent move and, other than lots of prayer and griping to friends, Lamott managed to let the scenario play out.

In print, Lamott balances her love for Jax and fascination with his many milestones -- hand clapping, blowing raspberries and sleeping through the night -- with the rest of her life's unfolding -- international travel, a book tour and the death of her beloved Uncle Millard, the family patriarch.

And though her early turn as a grandma may have caught her off-guard, the greatest surprise has been watching her son evolve into a hands-on, committed father.

Grace, she said, is truly amazing.

"You think something is stuck beyond repair and grace is constant WD-40," said Lamott. "You think how can that be enough? These problems are so big. I am constantly amazed at what a showoff God is."