This article offers information on the beginning and the development in Italy and abroad of technical assistance activities performed by IIS and later on by IIS Service srl. At the purpose, three subsequent periods are considered: a first one of affirmation of such activities; an intermediate one of consolidation of IIS on the market and of beginning of organization of its structure; a final one of further growth of such activities and of development and completion of IIS restructuring in order to prepare the partition which originated the IIS Group. The latter comprehends IIS Ente Morale (no profit distributing society), IIS Cert srl (Ltd) and IIS Service srl (Ltd), established at the beginning of 2011, and IIS Progress srl (Ltd), established at the beginning of 2013. In particular, the paper shows how, in some sixty years of activity, IIS gained a fame of seriousness, reliability and competence, that have made it one of the most comprehensive benchmarks in the field of welding, allied processes and connected techniques, appreciated everywhere it acted, in Italy, in Europe and in other continents. Finally, it is remembered that in 1988 IIS acquired with its own resources a modern and well-equipped headquarters in Genoa, that, in mid-2013, IIS Group owned various other regional offices and that at the time had in force some 225 employees (including some sixty graduate engineers and some one hundred technical licentiates), about half of whom are employees and managers of IIS Service srl. [ABSTRACT FROM AUTHOR]