The League for Socialist Action was a group of supporters of the US SWP Tendency in the Fourth International (United Secretariat) which split from the British International Marxist Group in the mid-1970s.
It produced a paper- Socialist Action – and a number of pamphlets.
We have 20 issues of their newspaper here:
and a small number of their pamphlets LSA Pamphlets
LSA members were active in the Labour Party and later merged again with the IMG in 1982 when its members too joined the Labour Party.
Do let us know if you can add to our collections of LSA publications.