Out of 28 countries in the European Union, the UK comes 18th - below some of the poorer countries of eastern Europe.
The EU-funded Milestone study looked at the number of inpatient beds per 100,000 young people.
With a rate of 9.4 beds for young people suffering from disorders such as psychosis and severe anxiety, the UK has fewer beds than Latvia, Lithuania and Estonia - with rates of 39.5, 31.5 and 21.
Sweden has the least with 1.2 beds and Germany has the most with 64 beds per 100,000 young people - over fifty times as many.
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An even lower ranking was seen in UK rates of child and adolescent psychiatrists - at 4.5 per 100,000 young people - with only Bulgaria, Hungary, Malta, Poland, Romania, Slovakia, having fewer.
The UK's relatively poor performance is despite having 939 public Child and Adolescent Mental Health Services (CAMHS) - by far the largest level of the countries in the evaluation.
The project, led by Warwick Medical School with researchers from seven other EU countries, highlights the disparity in mental health service provision across the region.
Researchers are calling for better national policies and improved access to mental health services for children and adolescents.
The figures are among findings to be presented in Westminster today, to mark the end of the study that aims to improve transition from CAMHS to adult mental health services across Europe.
It claims to be the first comprehensive evaluation of these services in Europe and examines young people's experiences for the first time.
The research highlights significant variations in the number of paediatric beds available - a measure of the capacity of those services - as well how services are delivered.
Project co-ordinator at Warwick Medical School Professor Swaran Singh said one way of bridging the transition had been investigated, but suggested further work was needed to test long-term outcomes for young people with emerging mental health problems.
Singh said: "The Milestone project is a genuine milestone in youth mental health research since for the first time it shows the nature and magnitude of the problem of transition from child to adult mental health services, something that has been often discussed but never quantified and understood in such a detailed and nuanced manner.
"With around a tenth of young people likely to experience mental health issues, it's a matter of concern that the approach to child mental health varies so dramatically across Europe.
"Our youth deserve better mental health care than they currently receive"
Architecture and functioning of child and adolescent mental health services: a 28-country survey in Europe, is published in the Lancet Psychiatry.