No World War in 1914
I concur with Derek Jackson.
If Russia failed to mobilize in response to Austria-Hungary's mobilization against Serbia following the assassination of Arch-Duke Franz Ferdinand, then there would have been no World War I--at least not in 1914. France only entered the war because of its anti-German treaty alliance committments to Russia, and Great Britain followed France into the war.
Still, given the tense climate of national/imperial rivalries in Europe in 1914, a major war was likely to break out eventually. Germany and Austria-Hungary feared growing Russian power, given its rapid industrialization since the mid-1890s. If Germany attacked Russia, then France and eventually Great Britain would have been drawn by their treaty committments (with Russia and each other) into a general European war against Germany and its Central Power allies.