Children across England will today learn which secondary school they will attend from this September, although thousands are expected to miss out on their top choice.
Last year, almost one in six 11-year-olds failed to get into their chosen school, according to official figures.
Letters will be arriving on the doorsteps of hundreds of thousands of families, on what is known as National Offer Day.
Siobhan Freegard, co-founder of parenting website Netmums, said that parents and children will have been through "months of worry and emotional turmoil" waiting to hear if they have won a coveted place at their first choice school.
And those that miss out are unlikely to give up, with one admissions lawyer warning that he expects to see many parents appealing against allocations.
Matt Richards, of schoolappeals.com, said he was expecting to see a growth in parents appealing because their child did not win a grammar school place.
He said there were potential applications for appeals on this issue countrywide, adding "it's probably down to people who can't afford private school anymore".
Richards added that many of these appeals are likely to be because the child involved did not pass the eleven plus exam, and the parents believe that there was a good reason for this.
"What we're noticing this year are far more parents willing to go down that road because they don't want the comprehensive, they want the good grammar."
Government figures show that in 2011, 79,000 children did not get the secondary school of their choice.
Nationally, 84.6% of 11-year-olds received an offer at their first choice, while 95.6% were allocated a place at one of their three preferred schools.
Freegard said: "We are seeing more areas around the UK becoming increasingly short on secondary school places - not helped by rising birth rates and cuts to the schools building programme.
"The secondary school a child attends can have a huge influence over their future - which is why both the parents and the child go through months of worry and emotional turmoil in the build up to this day, from selecting the right school through to finding out if they have been accepted.
"The effects of being told 'no' cannot be underestimated - telling a child that they can't go to school with the rest of their friends can make them feel like failure.
"It is essential that parents know that there is support and advice available to help them at this stressful time, and there are waiting lists and appeals that they can become involved with if needed."
Schools Minister Nick Gibb said: "There are still too many pupils trying to get into too few good schools. Parents in the most deprived areas of the country are often left to choose between weak schools, and this is no choice at all.
"Our school reforms will raise standards and create more good schools. We are turning around underperforming schools that are failing their pupils."