Functionalist housing developments were constructed in Stockholm between 1930 and1980, a period marked by rapid urban growth and expansion. Despite the wide variety ofurban spaces produced over these five decades, functionalism is commonly associated withthe rationalist codification and stylistic evolution promoted by the Modern Movement. Inorder to address this internal diversity, this study understands functionalism not as a unifiedstyle but as a design philosophy or approach, expressed through a multiplicity of forms—as it was originally formulated in the 1920s and later revisited around 1950 by architectssuch as Ralph Erskine. The research draws on Adolf Behne’s seminal 1923 text, in whichfour functionalist approaches to design are identified: expressionism, rationalism, a middleground between the two, and utilitarianism. While styles are often organised as a successionof discrete historical periods, design approaches are here conceptualised as strands thatcut across and persist through those periods. Case studies of housing developments wereselected on the basis of established classifications of Stockholm’s urban development phasesand subsequently analysed in relation to contemporary European trends and comparableexperiences, identifying the driving forces that shaped their final form. The study alsoexamines the extent to which Behne’s functionalist approaches remained relevant throughoutthe period under consideration and how they manifested in the selected cases. Finally, eachhousing development is interpreted through the interaction of three key factors: the mode ofstylistic expression, the underlying design strand from which the project emerges, and thedriving forces that informed its realisation.