Mills represented England at
youth and
under-23 levels. During the 1972–73 season, England manager
Alf Ramsey gave Mills his first international cap in a 1–1 draw with
Yugoslavia at
Wembley. Mills played at right back, a position which became more familiar to him with England than with Ipswich as his career continued. His second cap came in 1976 against
Wales and he had eleven by the end of the 1977 campaign. While his club had finally won a trophy, Mills' international career was in a semi-statuesque state.
Don Revie had given him a number of games at left back, including the opening qualifiers for the
1978 World Cup (a straightforward 4–1 win for England over
Finland, followed by a disappointing 2–0 defeat to
Italy) but Mills had to cope with much competition for both full back slots. After Revie's departure, successor
Ron Greenwood seemed to prefer
Liverpool's
Phil Neal at right back and
Leeds United's
Trevor Cherry at left back, with Mills as reserve for both. He did not play in any of the remaining qualifying games, and England failed to reach the finals. Mills, however, started to become a regular in the England set-up in 1978 though some confusion continued over his best position as, of the eight internationals during that year, he played six at left back (with Neal on the right) and two at right back (with Cherry down the left). Mills sacrificed his place in the final England game of 1978, against
Czechoslovakia, when
Nottingham Forest right back
Viv Anderson was handed his debut, becoming England's first black player. Another young debutant,
Kenny Sansom, emerged in 1979 to give Mills food for thought in the other full back slot, but he began to settle in at left back for his country as England qualified for the
1980 European Championships. Mills was named in Greenwood's squad but by now Sansom was an established option in the left back slot and he got the nod over Mills in England's opening two group games – a draw with
Belgium and a defeat against hosts Italy – before Mills returned for the final game against
Spain, which, despite an England win, saw their exit from the tournament. Mills played four England matches in 1981 – notably, they were all World Cup qualifiers for the
1982 tournament, with Greenwood happy to use less-experienced players like Anderson and Sansom in the friendly games which preceded them. When England beat
Hungary at Wembley in their final qualifier to reach their first World Cup in a dozen years, Mills won his 35th cap. Still switching flanks for his country when required (but rarely for club – he was almost always the left back), Mills played in just two of the preparation matches for the competition, but was named in the team as right back and captain (squad captain
Kevin Keegan was injured) when England played their first game of the tournament against
France in
Bilbao. England won 3–1 and Mills stayed in the side for the remaining group matches, both of which England also won, although he switched to left back for the final match to allow a run-out for Neal. Greenwood reverted to a Mills-Sansom full back pairing for the second phase, but two goalless draws against
West Germany and Spain (the latter of which finally saw Keegan's return to the team) sent England out of the competition. ==Coaching and managerial career==