Southgate is desperate to avoid more lurid headlines in the wake of what happened with Mason Greenwood and Phil Foden in Iceland - and will remind his squad of their responsibilities when they meet up at St George's Park on Monday.
Greenwood and Foden were axed and sent home in shame after smuggling two women into the team's hotel in Reykjavik to breach strict Covid-19 protocols.
Southgate has dropped the rising stars from his squad to face Wales, Belgium and Denmark at Wembley - and admits he had to send a clear message to the group that ill-discipline will not be tolerated.
He said: "There's a message needed to all players in all of our squads - seniors right through the age groups - that that's not how things are going to be done with England.
"We want high standards from people. Decisions send a message, really, and I think we have found that throughout the four years.
"Young people make mistakes and so you have to move forward from that, but there has to be a consequence. We've taken the decision to give them that reflection.
"They know that what they did wasn't acceptable. We needed that message to go out to all players who are involved with England at every age group.
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"I think you always have to work at culture. It's never embedded forever, it's constantly evolving, so you have always got to keep affecting that, keep addressing that and we will discuss the shirt, what it means to wear the shirt and some reminders on how we work.
"They have shown so many positives over the last years, but we had not been together for 10 months. We addressed some of that last time round, but obviously when something like what has happened has happened, we have to revisit that."
Southgate, however, has handed a reprieve to Harry Maguire and recalled the Manchester United captain to his squad.
Southgate was forced to drop Maguire from his last squad while he faced a court case in Greece following a drunken brawl with police on the island of Mykonos.
Maguire, 27, was given a suspended prison sentence after being found guilty of aggravated assault, resisting arrest and repeated attempts of bribery.
But the defender maintains his innocence and has appealed against the decision, which nullifies the conviction.
Southgate added: "I think I said last month there was absolutely no reason we couldn't pick Harry this time.
"He has been our most reliable defender over the last couple of years so it was not even a consideration that he would be in the squad or not."