Rad je dio projekta Specifična obilježja obitelji u riziku: doprinos razvoju kompleksnih intervencija, koji se provodi na Edukacijsko-rehabilitacijskom fakultetu Sveučilišta u Zagrebu, a financiran je od Hrvatske zaklade za znanost u okviru natječaja Istraživački projekti 2014. Cilj rada je istražiti, predstaviti i prodiskutirati različita razumijevanja kompleksnih intervencija i uz njih vezanih konstrukta i teorijskih pristupa. Krajnji cilj tog predstavljanja je konstruiranje operacionalne definicije koje će se u projektu koristiti. Pregled literature obuhvatio je radova koji se bave s jedne strane kompleksnim potrebama, problemima i populacijama, a s druge strane kompleksnim sustavima i intervencijama u području odgoja i obrazovanja, socijalne skrbi, pravosuđa i zdravstva. Nakon analize postavljene su operacionalne definicije pojmova kompleksne (indiviualne i obiteljske) potrebe i kompleksne intervencije te su generirane smjernice za planiranje i provedbu istraživačkog dijela projekta. This article is part of the project Specific characteristics of families at risk: contribution to complex interventions planning which is conducted at The University of Zagreb, Faculty of Education and Rehabilitation Sciences. The project is fully financially supported by Croatian Scientific Foundation under the Research Projects 2014. The aim of this paper is to find out, present and discuss different meanings and understandings of complex interventions, as well as theories and models they are based on. The final purpose of that presentation is to construct operational definition of complex interventions that is going to be used in this project. Literature on complex needs, problems and populations was reviewed parallel to literature covering complex intervention and complex interventional systems in the domain of education, health, especially mental health, social welfare and justice. After that, operational definitions of the notions of complex (individual and family) needs and complex interventions, as well as recommendations for planning and implementing research procedure were presented.