Germany- Wanted it's 'Place in the Sun', a large colonial empire. It also believed it should dominate continental Europe.
France- Naturally hated Germany since the war with Prussia in 1870. Invested heavily in Russia in an attempt to build an ally against Germany.
UK- Having only recently come out of 'splendid isolation', Britain mainly tended to it's empire. It saw Germany's naval build up as a direct challenge to the Royal Navy's supremacy at sea.
Russia- Saw itself as the protector of the Slavic people, and didn't take to kindly to Austria-Hungary's declaration of war against Serbia.
USA- Woodrow Wilson's preached about self-determination and freedom of the sea's, but was ignored by his British, French and Italian allies who all had colonial empires and used naval power to control them.