Described is an actuation mechanism for a medicament delivery device (1) having a needle (2) with a distal tip (2.1). The actuation mechanism comprises an outer sleeve (4) telescopically relative to the delivery device (1) and an inner sleeve (3) telescopically arranged relative to the outer sleeve (4). The outer sleeve (4) is axially translatable relative to the delivery device (1), and the inner sleeve (4) is axially translatable relative to the outer sleeve (4). In a first state, the inner sleeve (3) protrudes distally from the outer sleeve (4) and the outer sleeve (4) protrudes distally from the delivery device (1). In a second state, the inner sleeve (3) is contained within the outer sleeve (4). Movement of the outer sleeve (4) proximally relative to the delivery device (1) in the second state initiates delivery of a medicament in the delivery device (1).