After the age of nine years or so, it becomes more likely children will have a 'best friend' and may form more intense, longer-lasting friendships on the basis of a variety of shared interests and things in common.
Your child may be happy with just one friend, or be extremely popular with a large circle of friends. Alternatively, he may seem perfectly content on his own - sometimes because he has interests that are different from most other children his age, whether older or younger. If he's happy with the situation, that's fine. You only need to worry if he seems upset about rejection by friends.
Friendships can be a wonderful source of strength emotionally for children, and help their developing self-confidence.
It's right to worry if your child seems upset by a constant lack of friends. This can mean they're more vulnerable - not just to loneliness and low self-esteem - but to later problems such as lower academic achievement, or even eating disorders and depression.
Your child may be so shy that he has great difficulty reaching out to make friends. Alternatively, a bullying or very aggressive child may find other children avoid him.
However, there are children who don't fit into either of these extreme categories, but who just seem to be loners.
Not all of these children are troubled by it, so it's important not to overreact. While the vast majority of children do rely heavily on their friendships, there are some who seem quite happy without this, and many grow into resourceful, creative adults.
Teach negotiation and conflict resolution - talk to your child about how to listen to others, state his point of view assertively and how to compromise. Make your child's friends welcome in your home - don't judge your child's choices too harshly or force him to play with children you choose.
Make an effort to talk to other parents at school - this encourages children to get to know each other.
Find local activities - where your child will have opportunities to make friends outside of school, such as cubs, a drama group or swimming lessons.
Show love - this is invaluable as it help bolster your child's confidence, even if there are occasional friendship difficulties. Never show up your child or tell him off in front of friends.
Try not to interfere too much in matters connected with your child's friendships and social life - he should have the chance to sort these out in his own way whenever possible.
You may worry about your child getting in with a 'bad' crowd or making 'unsuitable' friends. This can be quite tricky because any moves you make to ban such friendships usually only make a child more determined to carry on with them. It's better to allow the friendship and to keep an eye on things, especially when in your own home. You can stress they must stick to your house rules - for example, no swearing or hitting.