after WW2, Yugoslavia had developed a unique economic system based on worker's self-management that provided a third way in the cold war between Western Capitalism and Soviet Communism. While it had it's fair share of issues, it was quite successful for much of it's history and brought years of peace, stability and prosperity that many in the Balkans look back fondly upon (especially considering what came after it)
however, in 1980 just after the death of Tito, the country began to enter a major economic crisis that brought about inflation, unemployment and drove the one booming economy to a grinding halt. it was a major shock at the time and as someone personally interested in Studying the Yugoslav experiment in a more market-focused form of Socialism, I've yet to figure out what even caused this sudden collapse of a once innovative and effective economic system.
What caused the collapse of the Yugoslav Economy in 1980? was it a result of the major oil crisis at the time, the large amount of foreign debt the country had accumulated, from contradictions stemming inherently from their worker-run system or as a result of deviating from it towards private enterprise and capitalist reform?
This is an excellent question, and I'm always happy to go down the rabbit hole of macroeconomic history.
As I'm sure you know, Yugoslavia was always the most Western of any socialist economy, and it had fairly decent economic ties to the West, the United States included. In point of fact, over the course of about a decade (1949 - 1961), Yugoslavia was importing a lot of western capital: the United States funneled in $2 billion in aid, and EEC banks brought in lots of investment as well (1). However, as early as 1961 we start to see that Yugoslavia's economy is fairly dependent on these foreign investments, and the country's deficit reaches $250 million. Within 3 more years, the deficit balloons to $800 million (1, 2)
This begins a cycle of deficit, reaching out to the IMF and West for help, only for reliance to increase and a deficit created again. By the mid-1970s, western credits were covering 90% of Yugoslavia's deficits. Then we have the global economic crises of the late 1970s and early 1980s. Across the board, external debt quintuples, and Yugoslavia's $3.4 billion in debt at the outset of the 1970s expands to $18.5 billion by 1981 (1, 2)
Now, external debt like this on its own is not inherently an economic death sentence, and it was actually significantly lower than many other countries. Depending on which historian you read and their own political views, you'll hear various “silver bullet” arguments: some argue the self-management economy was ill-conceived from the beginning, and it was the main factor to blame; others will argue that it was the World Bank and the IMF's stabilization programs that were to blame; others will argue that it was Yugoslavia's reforms in the 1970s at the same time as the oil shocks (3, 4). In my experience, the answer is "D," all of the above.
In the end, we have the economic collapse in the 1980s. Economic output declines, unemployment balloons, inflation explodes to over 200%, while the dinar was depreciating at an even faster rate than inflation. For the last time, Yugoslavia attempts to implement more IMF stabilization, but at that point it was too late. Croatia and Slovenia were doing significantly better than their federal counterparts, and in their eyes the government of Belgrade was useless at this point. They leave the federation within a day of each other in 1991, followed by Macedonia and Bosnia over the next several months. It's important to note that the economic collapse was not the sole driving force to the breakup, and there are an inordinate number of books and schools of thought you can read about the dissolution itself.
I hoped that answered your question, and if you have additional ones I'd be happy to answer them as best as I can!