When Torbjörn Dahlström (Onbird, Sweden), in a LinkedIn forum, asked "Was ITIL the first framework responsible for spreading the term SLA - Service Level Agreement? Or could it be found commonly before ITIL was created?", several seasoned ITSM experts unloaded their memory cells.

Robert Falkowitz (Concentric Circle Consulting, Switzerland) recalled "that in the early 1980s, before ITIL and before the Internet became commonly used, when 'managed services' and 'quality of service' were the buzzwords of telecom and datacom companies, one could contractually define the quality of service to be delivered." But he mentioned that he couldn't recall the specific use of the term SLA.

Carlo Figliomeni (TD Securities, Canada) pointed out that "in the early 80's before ITIL, these were called SMC Service Management Controls; The SLA was called DOU or Document of Understanding."
And he continued: "The SLA term was used back in the late 70's while I was at IBM. However it included also the objective as identified in the OLA, since OLA were not used until later on. While at IBM in the early 70's we used the term DOU and SMC and these terms proliferated to the IBM customers, until we moved from the tradition Data Processing to a Service model and at that time we used the term Service Level Agreement to measure how well we delivered the Service(s) to each of our customers..."

This was confirmed by Patrick Nightingale (Enigma Consulting, South Africa): "SLA or Service Level Agreement was indeed part of the System Management Controls (SMC) function and it was used to agree on the nature of the service and the terms of service delvery between customer (consumer) and the IT Department, dating from the late 1970's. ITIL has certainly played an significant role in refining and integrating the SLA into Service Management but it was not the originator of the SLA in the IT world."

Ian Clayton (Service Management 101, USA) also confirmed this: "we used the term SLA, and it included service level objectives (not targets) and was linked to internal 'operations contracts', in turn linked to team charters, in late 1970s, and when I was at EDS International (again pre ITIL) we used same terms.

Rick Lemieux (itSM Solutions, USA) recalled that he "spent the early part of my career working with service providers (ISP; carriers etc.) and we were using the term SLA then (I had not discovered ITIL yet) so I believe it was pre ITIL."

Bill Powell (ZeNETeX, USA) then came up with more details, confirming Carlo Figliomeni's memories: "The Yellow Books, aka the four volume set "A management system for the information business", second edition 1981 (I think first edition was 1980), has internal IT organizations managing to a service level plan and most of the other aspects of ITSM. This is the set that Ed Van Schaik was involved originally with. This set, based on IBM's experience in managing IT services in large scale data centers evolved into a lot of what the industry has today. From this IBM developed the IT Process Model and it also has the basis for the Component Business Model for IT. IT Process Model developed into Process Reference Model for IT and ITUP (to align with the same ISO/IEC process standards that COBIT 5 and ISO/IEC 20000 are now aligning with). It also covers the management system from a number of perspectives - process view, information view, business, service and systems view and strategic, tactical, operational views and other views. Very full exposition. This set, with related education and consulting services were provided to OGC (CCTA at the time) as input into ITIL V1.
I believe that at the time the 'best practice' for internal IT organizations was to have a 'service level plan' and exercise service control. External commercial service providers like Telcom, had service level agreements."

Steve Lawless (Wendia, UK) added "In the UK I was using the term SLA back in 1985 (Pre ITIL). Where the origin or impetus came from I forget, but were certainly had them."

In conclusion, Torbjörn Dahlström felt "that it was safe to say that ITIL picked up on the term rather than created it."

That ITIL contributed to the spreading of the wording should be obvious to all.