On 18 September 2008, Costello was appointed as chairman of the World Bank's new Independent Advisory Board (IAB) to provide advice on anti-corruption measures.

[5][6][7] During the 1980s, Costello was a solicitor at the law firm Mallesons Stephen Jaques,[8] then became a barrister and represented employers in some of Australia's best-known industrial relations disputes.

[9] In 1983 and 1984, Costello represented the National Farmers' Federation in legal action against the Australasian Meat Industry Employees Union (AMIEU).

For a time, he was an office-bearer of the Social Democratic Students Association of Victoria, an affiliate of the Balaclava Branch of Australian Young Labor.

In 1977, Costello was assaulted by a left-wing student politician, receiving mainstream media attention for the first time in his career as a result.

In 1990, Costello defeated sitting member Roger Shipton in a preselection ballot for the comfortably safe Liberal inner-east Melbourne electorate of Higgins, the seat once held by Harold Holt and John Gorton.

Costello made his maiden speech in May 1990 and mentioned "government should be subservient to the citizen; the Executive accountable to the representative parliament; and the monopoly give way in the face of the individual.

Costello believed Hewson fought everyone from Churches and Welfare groups over the GST to the Superannuation and Medicare organisations and recipients.

[17] Costello developed a higher profile following the 1993 election, becoming Shadow Finance Minister (though apparently failing to become deputy Liberal Party leader).

Inflation, interest rates[23] and unemployment all fell and remained generally low during Costello's term as Treasurer.

Until July 2005, Costello's own agenda of labour market deregulation remained blocked by the government's lack of a Senate majority.

[citation needed] In 2002, The Baby bonus scheme was reintroduced by the Federal Government of Australia in the 2002 budget was aimed at offsetting the expenses associated with bearing a child.

[27][28][29][30] In February 2006, Costello caused controversy during a lecture at the Sydney Institute when questioned about the government's refusal to legally recognise same-sex marriage.

[31] Also during the same speech, Costello criticised "mushy misguided multiculturalism," warning immigrants that the acceptance of Australian values was "not optional.

[20] When this did not eventuate, it is alleged that Costello became frustrated, particularly when Howard announced, in July 2003, his intention to lead the government into the 2004 election.

During the 2004 election campaign, Howard avoided saying whether he would serve a full term if re-elected, saying only he would remain as long as his party supported him.

[33] Howard denied the claims repeatedly, stating the continued public drama displayed "hubris and arrogance" and that the leadership was the party room's to decide, not a prize to be handed over by leaders to successors.

However, on 12 September 2007, amid renewed leadership tensions and a series of unfavourable public polls, Howard confirmed he would step aside well into the next term, if re-elected, and that Costello would be his "logical successor".

An exit poll of 2,787 voters by Auspoll, commissioned by Sky News, included a question on the statement "I don’t want Peter Costello to become Prime Minister".

[40] However, as opposition leader Brendan Nelson struggled, speculation mounted that Costello would change his mind and seek the leadership.

[42] Media attention immediately shifted to whether Costello's decision cleared the way for a leadership challenge by Malcolm Turnbull (who was the shadow treasurer at the time).

On 18 September 2008, Costello was appointed to the World Bank's new Independent Advisory Board, (IAB), which will provide advice on anti-corruption measures.

Costello's departure came just prior to the ETS crisis that lead to Malcolm Turnbull losing the Liberal party leadership to Tony Abbott.

[57] Costello responded by claiming that Howard "appears to be incapable of taking responsibility for the defeat of the government and for losing his seat of Bennelong.

[61][62] On 26 January 2011, Peter Costello was appointed a Companion of the Order of Australia (AC) for "eminent service to the Parliament of Australia, particularly through the development of landmark economic policy reforms in the areas of taxation, foreign investment, superannuation and corporate regulation, and through representative roles with global financial organisations".