Many of England's schools are struggling to recruit headteachers, a report warns.
More needs to be done to attract good candidates to fill the posts, according to The Future Leaders Trust, such as urging current school leaders to identify those with the potential to lead schools and help them to develop the skills they need for the job.
A survey conducted last year by the National Governors' Association (NGA) found that more than two fifths (43%) of schools polled said it was difficult to find good candidates when recruiting senior staff, the report notes.
At the same time, a poll conducted by the Future Leaders Trust in 2015 concluded that more than a quarter of heads questioned (28%) were planning to leave the post within five years, while over half said they did not expect to be a headteacher in 10 years.
Heath Monk, chief executive of The Future Leaders Trust, said: "Fewer people are applying to become heads and that means even fewer people are applying to lead schools that serve our most disadvantaged students. Without effective and inspiring leadership these children are losing out on the education they need.
"The talent is out there but many people need encouragement to understand they can step up. The solution is for existing heads to spot potential leaders in their schools and inspire them about headship."
In the report, Emma Knights, NGA chief executive, says not enough is known about the causes of the shortage in school leaders.
"Headship can be pressured and potentially lonely, and maintaining a healthy work/life balance can be difficult," Ms Knights says.
"Although a good chair and governing board will support the head, this is the nature of top leadership posts. Is school leadership less attractive because of the data-driven accountability? Or could it be that teachers don't seem to move around the country as much as other professionals?
"Has the shortage got anything to do with the fact that teaching is a female-dominated profession but women are under-represented in headship?"
One factor could be teachers' lack of experience in applying for jobs, Ms Knights suggests.
"Many governors have experience of recruiting in their professional lives, and the first time they are involved in school recruitment can be a surprise: the quality of some applications is shocking."
The move to create federations of schools and groups of academies run by a single trust could help solve the problem, Ms Knights suggests.
"We need to be more creative and braver: does every school actually need a traditional 'headteacher'?
"Groups of schools - federations and multi-academy trusts - give the opportunity for different roles that could help the recruitment problem.
"Allowing a head of school to lead teaching and learning, without the full business responsibilities of running an organisation, could be an all-round win."
A DfE spokesman said: "High quality school leaders are essential in delivering our vision of educational excellence everywhere.
"We are making good progress towards this goal with Ofsted rating 85% of schools as 'good' or 'outstanding' for leadership and management as well as a headteacher vacancy rate of just 0.2%, but we are not complacent.
"Our Talented Leaders initiative is placing outstanding headteachers into struggling schools and the National Teaching Service will place 1,500 teachers and middle leaders in under-performing schools by 2020."