Groups from 1881 were undoubtably a contributor toward the 1905 revolution but it can be argued on whether they were the main cause. The SRs were probably the biggest group fuelling the 1905 revolution.

The social revolutionaries were radical in their ideology, they believed that all land should be taken from the rich and given to the peasants along with completely getting rid of the Tsar. The SR's took radical action to achieve their goals such as assassinating the Tsars uncle grand Duke sergei. The SRs would be one of the main causes of the 1905 revolution as they had such a broad appeal, which certainly made them attractive amongst the uneducated masses, whom are the peasants and the peasants were desperate for change.

Peasants would want reform one way or another due to their poor standards of life. although Witte reforms seemed to be the best course of action for Russia, in the long term it was not. Witte increased tax on peasants to feel industrialisation which would have obviously increased peasants will for change since they had no money as it is. Workers in the cities will also feeling the aftermath of Wittes reforms, the economy started to slow down in the late 19th century which led to the workers real incomes falling by 20% which meant that imported goods or necessities couldn't be easily purchased when the price increased

Since the workers had such bad living and working conditions on the 22nd of January a priest Father Gapon gathered 150,000 people for a demonstration. Father Gapon had collected signatures of many people for petition to present to the Tsar for better living standards such as a 8 hour working day and free healthcare. When he and his protesters arrived at the winter palace they were massacred by guards this caused the St Petersburg soviet to be created by Trotsky which would have opposed the Tsars reign while offering a Marxism as am attractive alternative as to how Russia was controlled.

The Russo Japanese war was a main cause of the 1905 revolution, it caused protests in Russia due to poor performance.The Tsar was forced to sign a treaty as a sign of surrender to the Japanese this treaty Porthsmouth symbolised the decline of the Russians previously great image of ultimate power and control. The Tsar doesn't seem upto that standards of his previous kin since the battles Russia lost in the war people joining in the protests would've had other ideas on how to defend Russia, which may have caused the SRs support to grow

In conclusion the growth of the revolutionary groups were a main cause of the 1905 revolution this is because many of the other factors led to the formation of radical revolutionary groups such as the social revolutionaries and also added to their support, however they may not have shared ideology but change was desire by all