He was seen as an idealistic, but also polarizing politician. Throughout history, Dutch political leaders have tended to soothing manners - Den Uyl was one of a relatively few exceptions. People either loved him or hated him. Followers of his idealistic policies called him Ome Joop (Uncle Joop). He was criticized for creating a budget deficit (although this continued under future cabinets) and polarizing Dutch politics. Associated with Den Uyl was the maakbare samenleving (the makeable society, the idea that society is constructed and that government is a player in the construction). Another idea associated with Den Uyl was de verbeelding aan de macht (imagination in the driver's seat, the power of conceptual thinking, particularly in politics).
Den Uyl was married to Liesbeth den Uyl. They had 3 sons and 4 daughters. Of those Saskia Noorman-den Uyl became a member of parliament for the PvdA until 2006 and Xander den Uyl became a leading figure in ABVAKABO, one of the Dutch Labour unions.
Den Uyl's PvdA won the 1973 elections in alliance with the progressive liberal D'66 and radical Christian PPR, but failed to achieve a majority in parliament. After lengthy negotiations, he formed Kabinet-Den Uyl with the Christian-democratic KVP and ARP. This cabinet faced many problems. An early problem was the 1973 oil boycot following the Dutch support of Israel in the Yom Kippur war. Den Uyl said in a speech on national television that "things would never return to the way they were," and implemented fuel rationing and a stop on Sunday driving.
Between 1973 and 1977, the country’s economic situation turned ugly. The government’s budget deficit increased tenfold, inflation approached 10 percent, the unemployment rate doubled, and the current account went from positive to negative – the latter a critical problem in a country that rises or falls on foreign trade.
In 1977 the cabinet fell due to a conflict between Den Uyl and the KVP minister of Justice Van Agt. The PvdA entered the elections under the banner "Vote for the Prime Minister". The PvdA won by a landslide (it got over 33% percent of the votes, a relatively large share in the divided politics of the Netherlands at that time) and 53 seats. Coalition partner D'66 also went up, from 6 to 8 seats. However, coalition partner PPR lost nearly all its seats, making it impossible for Den Uyl to form a new government that could count on support in parliament. More than 200 days after the election, the CDA, a new party that was formed by Den Uyl's former coalition-members KVP and ARP (joined by the smaller CHU) formed a cabinet with liberal VVD, supported by a small majority of 77 seats (out of a total of 150) in parliament.
After being opposition leader from 1977 to 1981, Den Uyl returned to government in 1981. The PvdA formed a coalition with CDA and D'66. Den Uyl became vice-minister president and minister for Social Affairs and Employment. Van Agt, by now Den Uyl's Nemesis, led this cabinet. The cabinet was in constant internal conflict and fell after eight months. The elections of 1982 were won by the VVD. PvdA won little, CDA lost little and D'66 lost most of its seats. Den Uyl returned to parliament and led the PvdA in opposition until 1986. As leader of the main opposition party, Den Uyl - always a soft-spoken Atlanticist - provided cover for the government's controversial decision to place NATO cruise missiles on Dutch soil. In turn, this decision — and a similar one by the Belgian government — satisfied one of the West German conditions for the placement of cruise missiles and Pershing II missiles in West Germany.
"Twee dingen:..." ("Two things:..." In interviews, many of Den Uyl's answers started with these two words, sending a signal to the listener to drop any expectation of a simple yes or no.)