The terminology of ‘social engineers’ and ‘social engineering’ has been used in divergent ways in different historical contexts. Against the backdrop of the predominantly negative usages of recent decades, not least in critical evaluations of the Swedish welfare state, this article brings out the application that originally turned the terms into common goods. The business career of the expressions started in 1894 with an essay by the relatively radical Dutch industrialist J. C. Van Marken, and received its last major impetus in a book by the moderate American social reformer W. H. Tolman in 1909 (in French 1910). The main idea was that there was a parallel function to fill, alongside that of technical expertise, within modern industry. Dealing with human beings, solving problems within (and perhaps around) the workplace, was just as important for private companies as handling materials and machinery, not least in terms of efficiency and profitability due to motivation and loyalty among the workers. Van Marken’s and Tolman’s approaches are compared, mirroring the encounter between social reform and business management within ‘the labour question’ of the era. The functional parallel introduced by them, stressing the non-technical nature of the social engineer’s professional qualifications, including the talents of the diplomat, is also contrasted with the original version of the usages revolving around the machine metaphor (still the conceptual core in latter-day pejorative applications of the terminology), which was popularized as a positively-charged rhetorical tool in a religious context in 1911.