Training days for England's teachers should be quadrupled to 20 a year, costing £75m, a think tank proposes.
The Institute for Public Policy Research says the difference between excellent and bad teachers means pupils achieve more than a GCSE grade extra.
It argues that teaching does not attract the best graduates nor equip them adequately for the challenges of teaching in the 21st Century.
The government and teachers' unions say the country has the best teachers ever.
The IPPR commissioned the Centre for Market and Public Organisation to calculate the impact of teachers on pupils' attainment.
It did this primarily using data collected between 1999 and 2002 to evaluate the introduction of performance-related pay for teachers.
This involved about 6,000 pupils and 300 teachers in 40 schools which, it acknowledges, were not representative of all England's schools.
The study found a pupil taking eight GCSEs and taught by eight "good" teachers would score four to five more GCSE points than the same pupil in the same school taught by eight "poor" teachers. An "excellent" teacher had an even greater impact.
HAVE YOUR SAY
Some teachers may need to receive better training, but most importantly they need support in what is becoming a profession hampered by bureaucracy
The IPPR says this sort of impact is increasingly acknowledged by the government and by schools.
But there are concerns about how to improve up teacher quality.
It suggests that an effective 21st Century teacher needs to be a subject specialist who is also a "life coach", who uses classroom techniques that work with mixed ability classes.
But it says teaching attracts candidates in the top 30% of graduates in England, rather than only those with the very highest academic achievements.
And only one in 100 fails to qualify - a far lower proportion than in other countries, "suggesting that in England poor candidates are not being weeded out".
Once they begin work many teachers find they have little time to continue training, the report says.
Very few are fired for poor performance though Ofsted estimates that around 5% of teachers fall into that category.
The IPPR has several pages of recommendations, including a national written test for those wanting to train as teachers supplemented by psychometric testing, two years of training not one, more appraisals and 20 days' development a year - up from the current five.
It estimates that moving to a two-year training course would double the cost to £850m a year, while the extra development days would cost roughly four times the current amount, at £75m.
Schools Minister Andrew Adonis said: "Ofsted report that today's generation of teachers is 'the best trained ever, and the big rise in well qualified applicants to teaching in recent years supports this."
He added: "While we are not complacent about teacher quality, there are real improvements taking place."
The acting general secretary of the National Union of Teachers, Christine Blower, said: "I don't know what the IPPR report is talking about. There is overwhelming consensus that we have the best teachers ever.
"The idea of psychometric tests is a dead end which in many other walks of life has been shown to be highly dubious and very unreliable."
The IPPR report follows the comment by the chief executive of the General Teaching Council for England, Keith Bartley, that it was unacceptable that only 46 teachers from a workforce of around half a million had officially been assessed as "incompetent".
He called for teachers who "have more bad days than good" to be removed from their schools - and sent to another one in the area for retraining.
"The issue is how do we energise people in the profession," he said.
The leader of the NASUWT teachers' union, Chris Keates, said his claims were "unfounded, unnecessary and unacceptable" and "a witch hunt".