The Under-21 team is effectively the club's second-string side but is limited to five outfield players and one goalkeeper over the age of 21 per game following the introduction of new regulations from the 2022–23 season.

It was not solely reserved for the education of young players but also for the development of a modern approach to football from the roots up, as inspired by the success of the Hungarian national team featuring Ferenc Puskás that had humiliated England 6–3, and the great Real Madrid side of the late 1950s that dominated the European Cup.

Greenwood had inherited a young team of players from Ted Fenton, and the club was noted for its reliance on homegrown talent with Bobby Moore, Martin Peters, Geoff Hurst, John Lyall, Ronnie Boyce, John Sissons, Alan Sealey and Harry Redknapp all in the first team or periphery.

Further foundations had been laid with stalwart Ken Brown at the back, Malcolm Musgrove on the left wing (who was to leave in the second season), and the addition of John "Budgie" Byrne upfront.

Other players of the day included John Bond, Dave Sexton, Jimmy Andrews and Frank O'Farrell (later swapped for Eddie Lewis) and Tommy Moroney all part of an original 'Cafe Cassettari' club started by Fenton as a result of the restrictive budget.

[8] There [Cafe Cassettari], Allison would hold court, and the players would exchange views on the game and make tactical plans around the dinner table, illustrating their ideas with the use of salt and pepper pots.

The culmination of those years of hard work, on and off the field, was the Second Division championship in 1958 – the springboard to great cup successes at a much higher level in the mid-60s ... no one should underestimate the positive influence of Malcolm Allison's earlier role in Hammers' history.Cassettari's Café sat opposite the Boleyn Ground, and Fenton organized a deal that saw meals and a warm welcome for the club players at a price the club could manage.

[10] The tradition of mentorship lasted long into the 1960s even after Fenton had moved on and saw future managers John Lyall and Harry Redknapp pass through.

Fenton had been impressed greatly by the all-conquering Hungarians of the 1950s led by Ferenc Puskás, and the Cassettari program and development of the academy were at the core.

[10] Ernie Gregory said (of the 1950s diet) "We'd usually eaten fish or chicken and toast before then, but Dr. Thomas advised us all to eat steak and rice two hours before kick-off.

[8] At this time, three players who had come through the West Ham youth development system were beginning to find success in the England squad; they were Bobby Moore who debuted in 1962, Geoff Hurst and Martin Peters.

A bronze statue of these three players (and Everton defender Ray Wilson) holding the Jules Rimet Trophy aloft was erected in 2003 at the junction of Barking Road and Green Street close to Upton Park.

Paul Ince played his first game for West Ham in 1986, and went on to win more trophies than any other Academy "graduate", albeit with Manchester United.

Ferdinand and Carrick played against Lampard and Cole when Manchester United met Chelsea at the 2008 UEFA Champions League Final.

Recent Academy "graduates" include Glen Johnson, Billy Mehmet, Freddy Eastwood, Anton Ferdinand (younger brother of Rio), Elliott Ward, Mark Noble, Jack Collison, James Tomkins and Declan Rice.

[17] During the 2022–23 season, West Ham's under-18 won 26 out of 30 games in all competitions, winning the U18 Premier League South and the FA Youth Cup, beating Arsenal 5–1 at the Emirates Stadium to lift the trophy for the fourth time.

In the 2007–08 season, manager Alan Curbishley handed three graduates, Jack Collison, James Tomkins and Freddie Sears, their debuts.

Noble, Tomkins and Collison all went on to play an important part as West Ham beat relegation to finish 9th in the 2008–09 season.

Under him, Zavon Hines and Junior Stanislas have impressed after the August 2009 League Cup match against Millwall where they both scored in a 3–1 win.

It's very difficult to say why we've been so successful in youth terms; I suppose it's down to a number of factors but, most importantly, our recruitment area of east London and Essex is really fertile."

– Tony Carr, director of Youth Development at West Ham 1973–2010, quoted in an interview published by The Daily Telegraph 14 June 2004.

"The biggest single contributor to the current England national squad is not Manchester United, Arsenal, Liverpool or Chelsea, but the West Ham Youth Academy."