The 2015 Alberta general election was held on May 5, following a request of Premier Jim Prentice to the Lieutenant Governor of Alberta Donald Ethell to dissolve the Legislative Assembly on April 7. This election elected members to the 29th Alberta Legislature. It was only the fourth time in provincial history that saw a change of governing party, and was the last provincial election for both the Alberta Progressive Conservative and Wildrose parties, which merged in 2017 to form the United Conservative Party (although each ran a token candidate in the 2019 election).

The provincial Election Act fixed the election date to a three-month period between March 1 and May 31 in the fourth calendar year after the preceding election day in this case, April 23, 2012. However, the act does not affect the powers of the Lieutenant Governor to dissolve the Legislature before this period.

As a result of the election, the Alberta New Democratic Party (NDP) were elected to a majority government under leader Rachel Notley. The NDP formed government for the first time in Alberta history since the NDP's founding in the early 1960s.

The 2015 election is sometimes called the "Orange Chinook", a reference to the province's dramatic swing to the NDP, the NDP's orange colour and the weather shifts occasioned by strong Chinook winds that southern Alberta commonly experiences.

The NDP win ousted the PCs, who were reduced to third place in seats. Prentice resigned as PC leader and MLA for Calgary-Foothills on election night."Jim Prentice resignation as MLA too fast, strategist says" . CBC News, May 6, 2015.

The Progressive Conservatives (PCs) had a majority in the outgoing Assembly and had won every provincial election since the 1971 election, making them the longest-serving provincial government in Canadian history being in office for 44 years. This was only the fourth change of governing party in Alberta since becoming a province in 1905, and one of the worst defeats a provincial government has suffered in Canada. 31 PC MLAs lost re-election to the legislature, the largest number in one election in Alberta history. It also marked the first time in almost 80 years that a left-of-centre political party had formed government in Alberta since the defeat of the United Farmers of Alberta in 1935 and the Depression-era radical monetary reform policies of William Aberhart's Social Credit government.

The Wildrose Party under leader Brian Jean remained the Official Opposition, gaining four seats since 2012 despite winning 81,814 fewer votes and a 10.1% lower share of the popular vote than in the previous election. The Alberta Liberal Party and Alberta Party each won a single seat with Alberta Party leader Greg Clark becoming the party's first MLA. The Alberta Liberal Party lost four seats, only returning interim leader David Swann to the Legislative Assembly.

After the Calgary-Glenmore seat was allocated through a recount, 28 women were known to be elected in this election.

Following the election, Notley and her cabinet were sworn in on May 24.Notley, 11 cabinet ministers to be sworn in Sunday at legislature . Edmonton Journal, May 20, 2015.

Overall, across the province, 1,488,248 valid votes were cast in this election.

Background

In the 2012 general election the PCs lost a portion of their caucus, but were able to continue as majority government, despite their share of the popular vote decreasing to under 50%. The Wildrose Party formed the official opposition for the first time, while the other two parties in the Assembly, the Alberta Liberal Party and Alberta New Democratic Party (NDP), both held official party status with five and four seats respectively. On September 4, 2014, the PCs became the longest serving political dynasty in Canadian history, at 43 years, 5 days.

Prentice, who succeeded former premier and interim leader of the Progressive Conservatives Dave Hancock in September 2014, was not obligated to call an election until 2016. However, seeking a new mandate to pass his budget, he asked Lieutenant Governor Donald Ethell to dissolve the legislature on April 7. In accordance with Canadian constitutional practice, Ethell granted the request, beginning a month long campaign. The early election call was criticized by some as unethical, as it violated the fixed election dates specified in the Elections Act, but it was constitutionally valid and followed the general practice of the reserve powers of the Crown, specifically the constitutional convention of following the advice of the premier.

Results The NDP received the most votes (more votes than any other party) overall and in 54 districts (more than half the districts), though did not receive a majority of the vote overall nor in many districts. It received 40.6 per cent of the vote and captured 62 per cent of the seats in the Legislature.

Due to First-past-the-post voting, the NDP swept the Edmonton seats, won a majority of the seats in Calgary and just less than half of seats in rural Alberta. NDP MLAs were elected in all 21 Edmonton districts, 15 of the 26 Calgary districts and 18 of the 40 districts outside the major cities.

NDP candidates received over 50% of the votes in each Edmonton riding as well as the ridings of Sherwood Park, St. Albert and Lethbridge-West. All opposition (non-NDP) candidates received less than half the votes in the riding where they ran, except for the Wildrose candidates in Cypress-Medicine Hat, Strathmore-Brooks and Olds-Disbury, each of whom captured a majority of the district votes.

The election produced some very close races and small leads for some winning candidates. In Calgary Glenmore the winning candidate won with a lead of six votes over her leading contender. In Calgary McCall an NDP candidate won with less than 30 per cent of the vote; in Calgary Shaw an NDP candidate won with but 31 per cent of the vote; in Calgary South-East a PC won with only 32.5 per cent of the votes cast.

In many ridings the combined votes of the Progressive Conservative and the Wildrose candidates surpassed that of the NDP.

In some ridings such as Red Deer North, Spruce Grove-St. Albert, Calgary-Buffalo, Calgary-Varsity, Lethbridge East and Lethbridge West, the combined vote of the NDP and the Liberal candidates totalled more than 50 per cent of the district's votes, thus overwhelming the combined vote of the Conservative and Wild Rose candidate. This also held true for Calgary Mountain View where a Liberal was elected.

In many ridings no Liberal ran, which probably aided the NDP victory in those ridings. These included Lesser Slave Lake, Peace River, Edmonton-McClung, Sherwood Park, West Yellowhead and Whitecourt.

PartyVotesSeats604,518 30.8pp413,610 16.2pp360,511 10.1pp62,153 5.7pp33,221 0.9pp

!rowspan="2" colspan="2" style="text-align:left;" |Party !rowspan="2" style="text-align:left;" |Party leader !rowspan="2" style="text-align:center;" |Number ofcandidates !colspan="4" style="text-align:center;" |Seats !colspan="3" style="text-align:center;" |Popular vote* |- | style="text-align:center;" |2012 | style="text-align:center;" |Dissol. | style="text-align:center;" |2015 | style="text-align:center;" |% of Seats | style="text-align:center;" |# | style="text-align:center;" |% | style="text-align:center;" |Change (pp)

| style="text-align:left;" | Rachel Notley |87 ||4 ||4 ||54 ||62.1 ||604,518 ||40.62 ||+30.77

| style="text-align:left;" | Brian Jean |86 ||17 ||5 ||21 ||24.1 ||360,511 ||24.22 ||–10.06

| style="text-align:left;" | Jim Prentice |87 ||61 ||70 ||9 ||10.3 ||413,610 ||27.79 ||–16.17

| style="text-align:left;" | David Swann |56 ||5 ||5 ||1 ||1.1 ||62,153 ||4.18 ||–5.71

| style="text-align:left;" |Greg Clark |36 ||— ||— ||1 ||1.1 ||33,221 ||2.23 ||+0.92 Results compared to the Evergreen Party's results in 2012 | style="text-align:left;" |Janet Keeping |24 ||— ||— ||— ||— ||7,215 ||0.48 ||+0.09

| style="text-align:left;" |Len Skowronski |6 ||— ||— ||— ||— ||834 ||0.06 ||+0.03

| style="text-align:left;" |Naomi Rankin |2 ||— ||— ||— ||— ||182 ||0.01 ||= Results compared to the Separation Party's results in 2012 | style="text-align:left;" |Bart Hampton |1 ||— ||— ||— ||— ||72 ||0.005 ||=

| style="text-align:left;" colspan=2 |Independent |15 ||— ||1 ||— ||— ||5,932 ||0.40 ||+0.13

| style="text-align:left;" colspan="4" |Vacant |2 |1** |1.1 |colspan=3| |- | style="text-align:left;" colspan="3" |Total !400 !!87 !!87 !!87 !!100.0% !!1,488,248 !!100.00% !! |} * The total popular vote includes votes from voided Calgary-Foothills election. ** Incumbent Premier Jim Prentice disclaimed his victory in Calgary-Foothills. According to section 139 of the Alberta Elections Act,RSA 2000, c E-1 if a winning candidate disclaims their right to become an MLA before the end of the appeal period for the official results, that riding's election is declared void.

+ Elections to the Legislative Assembly of Alberta – seats won/lost by party, 2012–2015Party2012Gain from (loss to)2015NDPWRPCLibAlb ||4 || ||2|| ||44 || ||4 || || 54 ||17 ||(2) || || || 7||(1) || || || 21 ||61 ||(44) ||1||(7) || || || ||(1) || 9 ||5 ||(4) || || || || || || || 1 ||0 || || || ||1|| || || || 1Total 87(50) 3 (7) 52 (1) 4 (1) 86

The election resulted in a majority government led by the New Democratic Party.

The result in Calgary-Glenmore remained unresolved on election night, as incumbent PC MLA Linda Johnson and NDP challenger Anam Kazim finished the vote count in an exact tie of 7,015 votes each, necessitating a recount process. On May 15, the recount determined NDP candidate Anam Kazim won the riding by six votes.

The Alberta NDP had been leading in most polls since late April. They had been expected to do well in Edmonton, which historically had been more favourable to centre-left parties and candidates than Alberta in general. However, in a result that exceeded even the most optimistic projections for the NDP, Edmonton swung dramatically to support Notley, who represents an Edmonton riding. The NDP took every seat in the city, all by very large margins (4,000 votes or more with absolute majority support). The NDP also won 15 of the 25 seats in Calgary, the power base of the PCs for most of the previous four decades. The NDP also swept the province's third and fourth-largest cities, Lethbridge and Red Deer. NDP support remained relatively lower in rural Alberta, where they won only a handful of ridings in the north of the province, as well as some rural ridings around Edmonton.

Notley later said that she had known a week before the election that the NDP would win. She told the Canadian Press that she had been sitting in a hotel room in either Calgary or Lethbridge when she saw a very credible poll showing the NDP was poised to rebound from a mere four seats in the legislature – the minimum for official party status – to an outright majority. She was stunned at first, but recovered long enough to drop her plans for a whirlwind schedule to close out the campaign. Her original plan would have not only resulted in her looking extremely haggard in her first speech as premier-elect, but would have left her without time to begin a transition.