Alfonso XIII of Spain assumed power in 1902. Alfonso XIII became increasingly autocratic and in 1909 was condemned for ordering the execution of the radical leader, Ferrer Guardia, in Barcelona. He also prevented liberal reforms being introduced before the First World War.

Blamed for the Spanish defeat in the Moroccan War (1921) Alfonso was in constant conflict with Spanish politicians. His anti-democratic views encouraged Miguel Primo de Rivera to lead a military coup in 1923. He promised to eliminate corruption and to regenerate Spain. In order to do this he suspended the constitution, established martial law and imposed a strict system of censorship.

Miguel Primo de Rivera initially said he would rule for only 90 days, however, he broke this promise and remained in power. Little social reform took place but he tried to reduce unemployment by spending money on public works. To pay for this Primo de Rivera introduced higher taxes on the rich. When they complained he changed his policies and attempted to raise money by public loans. This caused rapid inflation and after losing support of the army was forced to resign in January 1930.

In 1931 Alfonso XIII agreed to democratic elections. It was the first time for nearly sixty years that free elections had been allowed in Spain. When the Spanish people voted overwhelmingly for a republic, Alfonso was advised that the only way to avoid large-scale violence was to go into exile. Alfonso agreed and left the country on 14th April, 1931.

The provisional government called a general election for June 1931. The Socialist Party (PSOE) and other left wing parties won an overwhelming victory. Niceto Alcala Zamora, a moderate Republican, became prime minister, but included in his cabinet several radical figures such as Manuel Azaña, Francisco Largo Caballero and Indalecio Prieto.

On 16th October 1931, Azaña replaced Niceto Alcala Zamora as prime minister. With the support of the Socialist Party (PSOE) he attempted to introduce agrarian reform and regional autonomy. However, these measures were blocked in the Cortes.

Azaña believed that the Catholic Church was responsible for Spain's backwardness. He defended the elimination of special privileges for the Church on the grounds that Spain had ceased to be Catholic. Azaña was criticized by the Catholic Church for not doing more to stop the burning of religious buildings in May 1931. He controversially remarked that burning of "all the convents in Spain was not worth the life of a single Republican".

The failed military coup led by José Sanjurjo on 10th August, 1932, rallied support for Azaña's government. It was now possible for him to get the Agrarian Reform Bill and the Catalan Statute passed by the Cortes. However, the modernization programme of the Azaña administration was undermined by a lack of financial resources.

The November 1933 elections saw the right-wing CEDA party win 115 seats whereas the Socialist Party only managed 58. CEDA now formed a parliamentary alliance with the Radical Party. Over the next two years the new administration demolished the reforms that had been introduced by Manuel Azaña and his government.

This led to a general strike on 4th October 1934 and an armed rising in Asturias. Azaña was accused of encouraging these disturbances and on 7th October he was arrested and interned on a ship in Barcelona Harbour. However, no evidence could be found against him and he was released on 18th December.

Azaña was also accused of supplying arms to the Asturias insurrectionaries. In March 1935, the matter was debated in the Cortes, where Azaña defended himself in a three-hour speech. On 6th April, 1935, the Tribunal of Constitutional Guarantees acquitted Azaña.

On 15th January 1936, Manuel Azaña helped to establish a coalition of parties on the political left to fight the national elections due to take place the following month. This included the Socialist Party (PSOE), Communist Party ( PCE), Esquerra Party and the Republican Union Party.

The Popular Front, as the coalition became known, advocated the restoration of Catalan autonomy, amnesty for political prisoners, agrarian reform, an end to political blacklists and the payment of damages for property owners who suffered during the revolt of 1934. The Anarchists refused to support the coalition and instead urged people not to vote.

Right-wing groups in Spain formed the National Front. This included the CEDA and the Carlists. The Falange Española did not officially join but most of its members supported the aims of the National Front.

The Spanish people voted on Sunday, 16th February, 1936. Out of a possible 13.5 million voters, over 9,870,000 participated in the 1936 General Election. 4,654,116 people (34.3) voted for the Popular Front, whereas the National Front obtained 4,503,505 (33.2) and the centre parties got 526,615 (5.4). The Popular Front, with 263 seats out of the 473 in the Cortes formed the new government.

The Popular Front government immediately upset the conservatives by releasing all left-wing political prisoners. The government also introduced agrarian reforms that penalized the landed aristocracy. Other measures included transferring right-wing military leaders such as Francisco Franco to posts outside Spain, outlawing the Falange Española and granting Catalonia political and administrative autonomy.

As a result of these measures the wealthy took vast sums of capital out of the country. This created an economic crisis and the value of the peseta declined which damaged trade and tourism. With prices rising workers demanded higher wages. This led to a series of strikes in Spain.

On the 10th May 1936 the conservative Niceto Alcala Zamora was ousted as president and replaced by the left-wing Manuel Azaña. Soon afterwards Spanish Army officers, including Emilio Mola, Francisco Franco, Juan Yague, Gonzalo Queipo de Llano and José Sanjurjo, began plotting to overthrow the Popular Front government. This resulted in the outbreak of the Spanish Civil War on 17th July, 1936.