Querying is a narrow, conventional process, and most rejections at this stage are about fit or presentation rather than about your book. Understanding the mechanics removes a great deal of the mystery and most of the avoidable errors.
Do you need an agent?
For the larger children's publishers, generally yes — most don't accept unagented submissions.
Some smaller and independent publishers do accept direct submissions, and for picture books that route is more open than it is in adult fiction. Worth researching before assuming an agent is the only path.
Research is most of the job
The commonest mistake is treating querying as a volume exercise.
Find agents who actually represent your category — picture books, middle grade and young adult are different specialisms, and plenty of agents handle one and not the others. Check their current list, check whether they're open to submissions, and read their guidelines, which differ in ways that matter.
An agent who represents nothing like your book will decline regardless of quality.
What a query contains
A short pitch. What the book is, in a few sentences. The category and age range. The word count. For picture books, often the full text alongside the query, since it's short enough. Submission channels vary — some agents take queries by email, others through an online form such as QueryManager or Submittable — and their guidelines will say which.
Comparable titles. Two or three recent books in your category that share something with yours — tone, structure, audience. Recent matters; comparing your book to a classic from decades ago reads as not knowing the current market.
A short bio. Relevant writing or professional background, briefly. If you have none, say less rather than padding it.
That's it. Query letters are short, and almost every first attempt is too long.
What to leave out
Your family's opinion of the book. That children love it. That it would make a good film or series. That it will teach children an important lesson. A plan for the sequels. Illustrations, unless you're the illustrator.
Simultaneous submissions
Querying several agents at once is normal and expected. You don't owe anyone exclusivity at the query stage unless they explicitly ask for it.
Query in batches rather than all at once, so that if something in your pitch isn't working you haven't exhausted the whole list before you find out.
Timelines
Slow. Weeks to months is normal, and many agents now state that no reply within a given period means no.
Chasing after a few days doesn't help. Keep a simple record of who you sent what to and when, and move on with the next thing.
What rejection means
Usually nothing you can act on. Form rejections carry no information — the agent may have just taken on something similar, or may not represent this category any more, or may simply have too full a list.
A personal note with a specific comment is different, and worth taking seriously because it's rare.
The fee rule
Agents are paid a commission on what they sell, typically a percentage of your earnings. They do not charge reading fees, submission fees, or upfront costs.
Anyone asking you to pay to be represented, or steering you toward a paid editorial service as a condition, is not operating as an agent. This is the clearest warning sign in the whole process.
While you wait
Write the next one. It's the only part of this you control, and the authors who get somewhere are generally the ones who were two books further on by the time the first one sold.