The party arose at a time when Slovakia was still part of Austria-Hungary, then it was one of the parties of Czechoslovakia. Together with the Slovak National Party, it was one of only two purely Slovak parties in Austria-Hungary and then in Czechoslovakia.
After a voluntary merger with other parties in November 1938 the resulting party became the dominant party of WWII Slovakia, where it was associated with the regime of Jozef Tiso.
Party chairmen were the Slovak priests Andrej Hlinka (1913-1938) and then Jozef Tiso (1938-1945).
The main newspapers of the party were Slovenské ľudové noviny (Slovak People's Newspaper, 1910-1930) and Slovák (The Slovak, 1919-1945).
As for the membership, the party mainly included former Slovak members of the Hungarian People's Party ("Néppárt", founded in 1895) and former members of the SNS. The programme of the party included liberal reforms (freedom of speech, universal suffrage etc.), national requirements and religious (Catholic) requirements.
In 1912, the SLS refused to support the strong Czecho-Slovak orientation of the SNS prevailing at that time and made a similar declaration as in 1905, again without formal effects. On July 29 1913, however, the SLS was finally created in Žilina as a separate Slovak political party in Austria-Hungary.
The Party's chairman was Andrej Hlinka, other leaders were Ferdiš Juriga and František Skyčák.
During WWI, the SLS (just like the SNS) stopped being politically active in order to prevent any possible pretext for accusations of activities against the Austrian-Hungarian state. The party, however, participated in the creation of the (2nd) Slovak National Council that existed from October 1918 to January 1919.
The party was also against Czechoslovakism (i. e. not considering Slovaks a separate ethnicity from the Czechs) and Atheism and Protestantism. During this period, the party can be characterized as a very conservative, strongly Catholic and anti-Communist party. As Hlinka put it in 1920 when the Czechoslovak Social Democrats won the election: "I will work 24 hours a day till Slovakia turns from a red Slovakia into a white and Christian Slovakia ". Its main voters were Slovak farmers, mainly because the party criticized the Czechoslovak land reform of 1920-1929.
The party received 17.5% of the vote in Slovakia in 1920 making it the 3rd largest party. Since the county elections in 1923, however, the party became the biggest party in Slovakia, receiving 34.4% in the 1925 and 30.3% in the 1935 general elections in the Slovak part of Czechoslovakia. Since the party was against Prague centralism, it was mostly in opposition. Only on January 15 1927 did it become a member of the Czechoslovak government coalition. After a controversial trial against the HSLS member Dr. Vojtech Tuka, who was accused of high treason, the HSLS left the government on October 8 1929.
In 1920, the party participated in the election together with the Czech People's Party under the name Czechoslovak People's Party. For the purpose of the general election of 1935 the HSLS joined with mainly the SNS, thus creating the "Autonomy Block", which ceased after the election.
After the death of the 74 years old Andrej Hlinka in August 1938, Jozef Tiso - until then the vice-chairman of the party- became the new chairman.
On October 6 1938, after the Czech part of Czechoslovakia had lost frontier regions to Germany through the Munich Agreement, the executive committee of the HSLS together with most other Slovak parties declared the autonomy of Slovakia within Czechoslovakia. Prague accepted this and appointed Jozef Tiso the Prime Minister of Autonomous Slovakia on the same day. HSLS became the dominant party in the subsequent Slovak governments.
On November 8, 1938, after the Slovak part of Czechoslovakia had lost some 1/3 of its territory to Hungary through the Vienna Award (Vienna Arbitration), the members of all parties (except for the Communist Party of Czechoslovakia) in Slovakia, i. e. the Slovak members of Czech political parties in Slovakia, merged with the HSLS and formed the Hlinka Slovak People's Party - Party of Slovak National Unity (HSLS-SSNJ). The Slovak National Party joined the HSLS-SSNJ on December 15.
This new party however already showed authoritarian tendencies, because it immediately prohibited Social Democratic, Communist and Jewish parties. In the December 1938 Slovak general election this new party consequently won 97.3% (out of which 72% went to candidates of the original HSLS). As from January 31 1939 all parties except for the HSLS-SSNJ, the Deutsche Partei (party of the German minority) and the Unified Magyar Party (party of the Hungarian minority) were prohibited.
Since 1939 however a conflict between two wings arose within the party. The conservative wing led by the Catholic priest Jozef Tiso, the president of Slovakia and chairman of the party, wanted to create a specific authoritarian and religious state of Estates. This wing controlled the leading posts of the country, party and the clerics. The other wing was inspired by the German model, were strong Anti-Semites, wanted to remove all Czechs and to create a radically fascist state (Slovak National Socialism). Their main organization was the Hlinka Guard (Hlinkova garda), which was controlled by the HSLS-SSNJ. The main representatives were the Prime Minister Vojtech Tuka and the Minister of the Interior Alexander Mach.
The problem of the fascist wing was that the population supported Tiso's wing, because the fascist wing was visibly demagogic, the fascist ideology was not compatible with most of the Slovak largely Catholic population and that the country was doing very well economically as compared to the neighbouring countries (incl. Germany).
Germany initially supported Tuka, but since 1942 when deportations of Jews started and a Germany-inspired act identifying Tiso and the HSLS-SSJN with the country itself (the "Führer"-principle) was forcibly adopted, Tiso's moderate wing had full support of Germany, whose only concern was the Jewish question and no problems whatsoever at German borders. This even enabled Tiso's wing to stop the deportations after some time.
The party ceased together with the liberation of Slovakia by Czechoslovak troops and by the Soviet Army in April-May 1945. Many of the party's members were persecuted during the Communist regime.