Based on the nature of its operations, the background of its personnel was mainly conservative middle class, but included a large number of students, especially those in technical studies.

In the Weimar Republic period, the TN was seen as a threat by the working class and thus aroused the animosity of trade unionists, and more particularly the Communist Party of Germany.

As economic conditions improved (after about 1925) and strikes became less common and less aggressive, the TN was able to shift its activities into public welfare areas such as disaster relief (Katastrophendienst), with respect to floods, fires, industrial accidents, bridge and railway collapses; as well as responding to motor vehicle accidents in the countryside.

Throughout the Third Reich the TN, within Germany, focused on civil defence — air raid rescue, general disaster response, and relief work.

In addition to working within Germany, the TN was active in Nazi-occupied countries from September 1, 1939 as Einsatzgruppen, which followed the Wehrmacht and restored vital services and functions in Poland, France, Belgium, Netherlands, Luxembourg, and Norway.

Local TN branch organisations were formed in some occupied countries, notably as the Technische Noodhulp in the Netherlands and as the Teknisk Nødhjelp in Norway.