Hi @simbameow ,    Oh, the politics of children's birthday parties- I can strongly relate to this post, we recently had the first ever 'big' party for my youngest, who also just turned 4. It can be a bit of a minefield I've found- chasing up RSVPs, not being sure if people will turn up, it goes on... I think I would just take an approach of being honest in an age appropriate way, and say that his friend really wanted to come, but his family had other plans that day so he couldn't make it.  Sometimes I think that these situations can be tougher on us as parents than it is on the kids - I can understand that you'd be feeling worried about damaging the friendship (and possibly a bit disappointed/ frustrated with his best friend's mum), but I imagine that your son may be a bit oblivious to those nuances.    Can you suggest that they maybe have a special play date/ play at the park another day?    I also just thought I'd suggest some of the great resources over at the Raising Children's Network over here. They have a lot of really good material developed by experts on preschooler/ school aged kids', their development, and ideas for how to support young kids in navigating friendships. We focus more on young people aged 12-25 at ReachOut - I know that I've found the RCN articles and resources really helpful as a parent myself :)  ... View more