The Croatian Spring (Croatian: Hrvatsko proljeće, also called masovni pokret or MASPOK, for "mass movement") was a political movement from the early 1970s that called for democratic and economic reforms in Croatia as part of SFR Yugoslavia.
The 1960s and 1970s in Croatia were marked by a general emancipation from the Stalinist policies employed in Yugoslavia after World War II. Despite significant conservative resistances, the country underwent major reforms, including economic reforms that in 1964/1965 started to introduce a market economy, and the democratization of the League of Communists of Yugoslavia between 1966 and 1969 which led to giving a bigger role to the Leagues of Communists of each individual republic and province.
Political demands 
Things were set in motion just nine months after the removal of Aleksandar Ranković, when a group of 130 influential Croatian poets and linguists, 80 of whom were Communists, published a Declaration on the Status and Name of the Croatian Standard Language in March 1967. After 1968 the patriotic goals of that document morphed into a generic Croatian movement for more rights for Croatia which received grassroots support, especially amongst many student organizations which actively started to voice their support for the cause.
A younger generation of reformer politicians in the republics' Communist Party organizations gave the movement a momentum in an effort to overcome the Party monopoly and to expand various civil rights.
The right to take pride in one's history was a prominently featured topic. This irritated Tito's communist government.
Among the issues raised was the practice by the Yugoslav People's Army to send people on mandatory military service into other republics rather than leaving them in their home republic.
There were also attempts to bring the notion of including Herzegovina into Croatia to the attention of the authorities (similar to the Banovina of Croatia that existed within the Kingdom of Yugoslavia from 1939 to 1941), but this was far from anything that the movement leaders were proposing. In fact, such red herrings were often used to denounce the demands related to decentralization and autonomy as expansionist and ultimately separatist.
Economic issues 
In the early days of the movement, the Croatian political leadership voiced demands for a democratization and decentralization of the economy, which would have allowed the republic to keep more of the profits made within Croatia, as opposed to using the income from tourism and from emigrants to avert economic ruin.
The economic problems in Yugoslavia at the time contributed to increased economic emigration, and these economic problems particularly affected Croatia, despite the fact it had been the source of the majority of the income from tourism and that 37% of all Yugoslav emigrant workers had come from Croatia.
Croatian economist Vladimir Veselica became known during this period for writing about the how Croatia had failed to profit from the disproportionately small amount of foreign currency that had entered Yugoslavia through Croatia. An independent National Bank of Croatia would have allowed for a fairer distribution of profits. By waiving the right to use the federal bank of Yugoslavia, the republic would also have to waive its right to use the federal fund for underdeveloped regions.
At the 10th session of the Central Committee of the League of Communists of Croatia held on 15 January 1970, Savka Dabčević-Kučar presented a quality paper on what she described as petty rhetoric about how Croatia was getting harmed in Yugoslavia. Croatian 1968 GDP per capita was 25% above national average, among other positive statistics. Croatia used only 16.5% of the money from the federal solidarity fund between 1965 and 1970, while the Yugoslav government used 46.6% mostly for the least developed region Kosovo and Metohija. Concerns were also raised about the monopoly of the Yugoslav Investment Bank and the Bank for Foreign Trade from Belgrade on all foreign investments and trade.
Public unrest 
The movement organized demonstrations in 1971 and thousands of Zagreb students publicly protested.
Three Croatian linguists, Stjepan Babić, Božidar Finka and Milan Moguš, published a spelling and grammar textbook in 1971 called Hrvatski pravopis (Croatian Orthography), rather than the forced Srpskohrvatski (Serbo-Croatian). It was summarily banned. However, one copy survived and found its way to London where it was printed and published.
The Yugoslav leadership interpreted the whole affair as a restoration of Croatian nationalism, dismissed the movement as chauvinistic and had the police brutally suppress the demonstrators. In 1971, Soviet Union leadership applied additional pressure on Josip Broz Tito directly by Leonid Brezhnev and indirectly by its ambassadors to Yugoslavia, to assert control of the Communist party within Yugoslavia, ostensibly adhering to the Brezhnev Doctrine.
After the calls to the student strike, in December 1971 Tito persuaded to resign some unreliable, in his view, public figures like Savka Dabčević-Kučar, Miko Tripalo and Dragutin Haramija and make a sweep in Croatian communist party and local administration. Many student activists were detained and some were even sentenced to years of prison. Some estimate that up to two thousand people were criminally prosecuted for participation in these events. Among those arrested at this time were future president of Croatia Franjo Tuđman and dissident journalist Bruno Bušić. There were several other notable political prisoners in Croatia from this period.
The social and political conservative forces engaged in a repression that prevented the final reforms that would have made Yugoslavia a true federation of sovereign republics and provinces, instead reducing both the Yugoslav political concept and its nomenklatura to a kind of "real socialism" that lacked potential.
In 1974, a new federal constitution was ratified that gave more autonomy to the individual republics, thereby basically fulfilling some of the goals of the Croatian Spring 1971 movement.
Several student leaders from the Croatian Spring later emerged as influential political figures after the collapse of communism. Franjo Tudjman became the first President of Croatia, Šime Đodan became a member of parliament and a one time Minister of Defence, Ivan Zvonimir Čičak became the leader of the Croatian Helsinki Committee for Human Rights. Dražen Budiša became the leader of the Croatian Social Liberal Party. Savka Dabčević-Kučar, Miko Tripalo and Dragutin Haramija became founding members of the new Croatian People's Party.
The fourth edition of the Babić-Finka-Moguš Hrvatski pravopis is used today as a standard definition of the Croatian language.
- CPSR 2012, pp. 8.
- Rusinow, Dennison (October 2012). "Facilis Decensus Averno". Croatian Political Science Review (in Croatian translation by Dejan Jović) (Faculty of Political Science, University of Zagreb) 49 (3): 52–55; 58. ISSN 0032-3241. Retrieved 2013-05-07.
- Rusinow, Dennison (September 1972). "Crisis in Croatia: Part II: Facilis Decensus Averno (DIR-5-72)". American Universities Field Staff Reports, Southeast Europe Series 19 (5).
- Matković, Hrvoje (December 2008). "Memoarska literatura o hrvatskome nacionalnom pokretu 1971. godine". Journal of Contemporary History (in Croatian) (Zagreb: Croatian Institute of History) 40 (3): 1149. ISSN 0590-9597. Retrieved 2013-05-07.
- CPSR 2012, pp. 7-8.
- Ivo Banac (20 November 2011). "Kako su Rusi lomili Tita i slomili Hrvatsku" [How the Russians pressured Tito and broke Croatia]. Večernji list (in Croatian). Retrieved 20 November 2011.
- CPSR 2012, pp. 9.