This study examines how an environmental organisation in Russia, Save-Shihan, uses social media to construct its claims during grassroots mobilisation and compares the use of two platforms throughout this process. It also analyses how Save-Shihan constructed its claims during the mobilisation against the mining of a sacred hill (Kushtau) in August 2020, and compares its use of Telegram and Vkontakte (VK). The former platform stands against state censorship, whilst the latter was then owned by a Kremlin-friendly oligarch. The findings demonstrate that Save-Shihan employed the regime’s narrative on acceptable mobilisation by presenting its claims as patriotic, legal and legitimate. Additionally, throughout the mobilisation both platforms were used to bring visibility to the conflict, coordinate activity, elevate local voices, display solidarity and for educational purposes. However, following the state’s temporary blocking of Save-Shihan’s VK account, the content posted there differed to Telegram, which resulted in some significant differences between the platforms’ uses. The implications of this study are threefold. Firstly, it is empirically relevant because it provides insight into how the unclear boundary between state sanctioned and unsanctioned mobilisation is navigated during mobilisation and the framing of its aims. Additionally, although Save-Shihan is one group, it was part of a larger mobilisation process which ultimately was successful, meaning other groups can learn from this case. Secondly, it demonstrates that whilst VK and Telegram were broadly used for similar purposes, there are some significant differences. This contributes to the literature on Russia’s social media landscape and shows that a platform’s relationship with the state, and the state’s actions in relation to it, influence how activists perceive and use social media during mobilisation. As will be later established, in the context of an increasingly repressed digital sphere, such differences are likely to become more important for activists. Lastly, this study brings visibility to an active and less-studied dimension of Russian civil society: grassroots mobilisation and informal organisations.