Write your kid a letter every birthday, and seal it

Quick answer: One handwritten page in the week of each birthday. Write about who they are right now, not who you hope they'll become. Seal it, keep every letter in one box, and hand over the whole stack the week they leave home.

Nobody writes these for the reason they think. You think you're writing to your kid. You're really writing to a 30-year-old sitting on the floor of a first apartment, opening envelope number six and finding out what his father noticed when nobody else was keeping track.

The night before

It's 10:40 on a Thursday. The dinosaur cake is under foil on the counter. There's a stack of wrapped presents in the hall closet, and you've got a legal pad and twenty minutes before you're useless.

Don't start with "Dear son, as you turn seven, I want you to know how proud I am." That sentence could go in any card at any drugstore. Start with the thing only you saw this year.

You eat your crusts first so the middle is waiting for you at the end. You asked me in the truck whether worms have moms. You were terrified of the hand dryers at Costco in March, and by August you were racing your sister to them.

That's a letter. By ten he won't remember being seven at all. You're the only archive he's got.

What goes in it

Keep it to one page. A page is something you'll actually finish every year, and eighteen of them make a stack a person can read in one sitting. Ten-page letters get abandoned at age four.

Over the years, these are the things that earn their space:

• What they're like right now. Favorite food, the phrase they say constantly, who their best friend is, what scares them. Boring to you, priceless to them later.
• One moment from the year. A single scene, told plainly. The day she rode without training wheels and immediately rode into the neighbor's hedge.
• Something you got wrong. Short and honest. "I yelled about the spilled paint and it wasn't worth it." A kid who finds out at 25 that his dad knew he blew it sometimes learns more from that line than from any advice.
• A little about you. What you were working on, what kept you up at night. They'll want to know who you were at 34. (Your kid is already learning plenty from your work habits. The letter lets you explain a few of them.)
• One thing you're proud of that isn't an achievement. Not the trophy. The time he gave his last pretzel to the kid who dropped his.

Handwrite it. Your prose won't be great, and it doesn't need to be. Your handwriting is the part they'll keep. Use a pen with archival pigment ink, like a Sakura Pigma Micron, so it doesn't fade to a ghost in twenty years.

What stays out

The letter has one job: show the kid who they were and who saw them. Anything that turns it into something else wrecks it.

No lectures. Every dad wants to slip a sermon on compound interest into the age-nine letter. Save it. Advice ages badly and reads like homework. Write what you noticed, not what you think they should do.

No grading. "You worked hard in math this year but need to focus" belongs on a report card. A letter that keeps score becomes a document they dread opening.

No adult problems. If money was tight or your marriage had a rough year, you can say it was a hard year at home. You don't explain why, and you never, under any circumstances, use the letter to make your case against their mother. That letter will sit in a box for a decade and go off like a land mine.

And no performing. If you catch yourself writing for an imagined audience, the grandparents or a future wedding toast, cut it. Write it like nobody else will ever read it. Mostly, nobody will.

Seal it or let them read it?

Seal it. This one has a clear winner.

Some families read last year's letter out loud at every birthday dinner, and it's a sweet tradition. It costs you honesty, though. You'll write differently knowing a nine-year-old will hear it in front of his cousins. You'll leave out the hard year, the thing you got wrong, the worry you had about him. Those are the exact lines that make the stack worth having.

A nine-year-old reading his own letter also reads it like a report card. He's looking for whether he did well. An adult reads it for the person who wrote it.

So seal each one in an envelope marked with their age and the date. Tell them the letters exist, though. Knowing there's a box filling up year after year, and that it's for them, is a gift by itself. You'll be surprised how often a twelve-year-old asks how many are in there now.

Store them in one place. A fireproof document box on a closet shelf is ideal. Not the attic, where summer heat cooks paper, and not scattered across three junk drawers. Snap a photo of each page before you seal it, in case the house burns or the box gets lost in a move.

The years you'll want to skip

Somewhere around fourteen or fifteen, there'll be a birthday when your kid barely speaks to you. He slammed a door that morning. You took the phone two weeks ago and he hasn't forgiven you.

Write that letter anyway. It might be the one he rereads most.

Don't write the grievance. Write what you see underneath it. You're taller than your mom now and you duck through the kitchen doorway like you're not sure of your own size. You're angry at me a lot this year. I get it. Then hold the line, because the letter isn't the place to cave either: I took the phone and I'd do it again. I'm sorry I didn't explain why sooner. A servant with a backbone, on paper.

Some years you'll be wiped out. Fifteen tired minutes beats a skipped year. If you do miss one, say so in the next letter. Don't backdate a fake one in March to cover your tracks. He'll notice. Kids always do.

If you're starting late, with a ten-year-old, start now. Write one opening letter covering what you remember of the early years, labeled as exactly that, and go year by year from here.

If their mom wants to write her own, great. Two stacks, not one jointly signed letter. Two voices are worth more than a committee.

Handing over the box

Not at the graduation party. That's a crowded day, and you've already got the one thing worth saying to get right.

Do it the week they leave home. Put the box in the car with the bedding and the shower caddy, or hand it over on the last night with a sentence and no speech. "These are yours. One for every year. Read them whenever."

Then leave the room.

Don't ask how it went, and don't hover. Maybe he reads all eighteen that night in a dorm with the lights off. Maybe he doesn't open the box for six years, until his own kid is born and he suddenly wants to know what his father was thinking at 3 a.m. with a baby who wouldn't sleep. Both are fine. You weren't writing for a reaction.

You'll never be in the room when he reads the one from when he was seven. So write it that way, starting this year, with the crusts and the worms and the hand dryers at Costco.