The first level of living survey started within the framework of a governmental commission set up to study the prevalence and problems of low incomes. Their task was broadly defined, so beside a range of studies on income and income distributions they also commissioned a group of sociologists, headed by Sten Johansson, to study the distribution of welfare in Sweden more generally. The study by Johansson and his colleagues, undertaken in 1968, came to be known as the Level of Living Survey. From the beginning it was not the longitudinal aspect that was the novelty, but rather the fact that a wide spectrum of living conditions was studied with the survey method as such. The division of level of living into different components, inspired by the work within the UN, resulted in the following list of components included in the Swedish Level of Living Surveys: Health and access to care; Employment and working conditions; Economic resources; Educational resources; Family and social integration; Housing and neighbourhood facilities; Security of life and property; Recreation and culture; Political resources. The first survey was based on a 0.0001 random sample of the Swedish population aged 15 to 75 years of age. The interviews were made face-to-face according to a structured questionnaire covering all areas listed above. A large number of questions were asked dealing with a variety of aspects within each area. The 1968 survey was to be repeated in 1974, and the decision was made to stick to the original sample but also include new cohorts of young people and immigrants arriving to Sweden in between the survey periods. Dropped from the sample was those above 75 years of age and those who had either emigrated or died. In 1981 the third Level of Living Survey was conducted with the same sample design and by and large with the same questionnaire. When Johansson left the project in 1982 Robert Erikson became the project leader. Erikson was project leader for the fourth level of living survey, conducted in 1991. During the project period Jan O. Jonsson and Johan Fritzell also were directors of the survey work. The 1991 survey was conducted with basically the same design, except for the fact that the youngest age bracket now became 18 instead of 15. The 1991 survey was enlarged in several respects. An obvious drawback of the panel design in the Level of Living Surveys is the relatively large time-span between each survey. Partly in order to fill in these missing years the 1991 questionnaire includes a work-life history section, and educational and family histories as well, thereby broadening the longitudinal aspects of the study. A second novelty was a specific survey to all individuals previously within the sample but excluded in the 1991 survey, due to the upper age limit. The sample included all persons older than 75 in 1991 who had previously been included in the Level of Living Survey sample and had been interviewed at least once. The interviews included most of the welfare components, with the exception of work related questions and education. Instead, more detailed data on health status and functional abilities was collected, partly by means of simple test performed during the interview. The third major extension was a separate work-place study consisting of interviews with managers at the work-places of all individuals who were employed at a work-place with at least ten employees.

År 1968 genomfördes på låginkomstutredningens initiativ den första levnadsnivåundersökningen (LNU), en undersökning som blivit stilbildande. Såväl i den löpande svenska statistikproduktionen genom SCB:s ULF-undersökningar som i andra länder har undersökningar etablerats som bygger på LNU:s koncept. Grunden är att ett riksrepresentativt urval av den vuxna svenska befolkningen intervjuas om sina faktiska levnadsförhållanden inom en rad områden som är centrala för människors liv, t.ex. hälsa, ekonomi, fritid, boende, politiskt deltagande och sysselsättning/arbetsförhållanden. År 1974 och 1981 ställde Riksdagen medel till förfogande för ytterligare två levnadsnivåundersökningar. År 1991 genomfördes återigen en replikation, då finansierad av åtta olika forskningsråd. Vid alla dessa tidpunkter har i huvudsak samma frågor om levnadsvillkor ställts, men i LNU91 skedde en metodutveckling med ett inslag av fler frågor av retrospektiv natur (fr a om intervjupersonernas sysselsättningar genom åren).Dessutom utfördes 1991 en intervjuundersökning med de högsta cheferna på de arbetsplatser där intervjupersonerna i LNU 91 var anställda (se Arbetsplatsundersökningen 1991). År 2000 genomfördes en ny levnadsnivåundersökning (LNU2000), för femte decenniet i rad. Den finansieras av Vetenskapsrådet (VR) och Forskningsrådet för Arbetsliv och Socialvetenskap (FAS) via deras gemensamma kommitté för longitudinell forskning. Kopplat till denna nya LNU gjordes också en separat studie av barn och ungdomar (10-18 år) som bodde i samma hushåll som intervjupersonen i LNU (Barn-LNU). Även denna gång adderades en Arbetsplatsundersökning (APU 2000). I de tidigare undersökningarna har frågorna till stor del ställts till samma personer, vilket innebär att en betydande "panel" - nästan 3.000 individer - har intervjuats vid samtliga fyra tillfällen. Även år 2000 återkom man i stor utsträckning till dessa tidigare intervjuade individer. Panelansatsen gör att man får större möjligheter att svara på centrala frågor om människors levnadsnivå. Bara genom att följa enskilda individer över tid kan man avgöra t.ex. uppväxtvillkorens betydelse för senare livsvillkor, vilken betydelse arbetsförhållandena har för människors hälsa senare i livet, vilka konsekvenser förändrade familjeförhållanden har eller vad vuxenutbildning betyder för vilket arbete man får. I de fall de intervjuade samtyckt, har intervjuerna i levnadsnivåmaterialet, kompletterats med uppgifter om bland annat inkomster. Den därigenom skapade databasen har möjliggjort omfattande beskrivningar och analyser av välfärden i Sverige från sent 1960-tal fram till början av 1990-talet, bland annat av hur välfärden utvecklats för män och kvinnor, hur den fördelas mellan olika ålders- och socialgrupper och mellan boende i olika ortstyper. Resultaten har publicerats i ett trettiotal avhandlingar, många rapporter och hundratals publicerade artiklar, främst skrivna av forskare knutna till Institutet för social forskning (SOFI), som sedan 1972 haft ansvaret för LNU.

The first survey was based on a 0.0001 random sample of the Swedish population aged 15 to 75 years of age. The 1968 survey was to be repeated in 1974, and the decision was made to stick to the original sample but also include new cohorts of young people and immigrants arriving to Sweden in between the survey periods. Dropped from the sample was those above 75 years of age and those who had either emigrated or died. In 1981 the third Level of Living Survey was conducted with the same sample design. The 1991 survey was conducted with basically the same design, except for the fact that the youngest age bracket now became 18 instead of 15.The first survey was based on a 0.0001 random sample of the Swedish population aged 15 to 75 years of age. The 1968 survey was to be repeated in 1974, and the decision was made to stick to the original sample but also include new cohorts of young people and immigrants arriving to Sweden in between the survey periods. Dropped from the sample was those above 75 years of age and those who had either emigrated or died. In 1981 the third Level of Living Survey was conducted with the same sample design. The 1991 survey was conducted with basically the same design, except for the fact that the youngest age bracket now became 18 instead of 15.