Yes, the assassination of Archduke Franz Ferdinand of Austria on June 28, 1914, is widely considered a significant catalyst for the outbreak of World War I. While it was not the sole cause of the war, it acted as a trigger that set off a chain reaction of events leading to the conflict.
The assassination was carried out by Gavrilo Princip, a member of a nationalist group seeking independence for the Slavic peoples under Austro-Hungarian rule. This act led Austria-Hungary to issue an ultimatum to Serbia, where the nationalist group was supported. Serbia's response to the ultimatum was deemed insufficient, leading Austria-Hungary to declare war on Serbia on July 28, 1914.
The complex web of alliances and treaties in place at the time rapidly escalated the situation. Russia mobilized to support Serbia, leading Germany to declare war on Russia, and subsequently on Russia's ally, France. The United Kingdom entered the war after Germany invaded Belgium as part of its war plan against France.
In summary, while there were multiple underlying causes of World War I, including militarism, alliances, imperialism, and nationalism, the assassination of Franz Ferdinand was the immediate event that triggered the outbreak of the war.