Abstract Study question What concepts and concept definitions (including normative meanings) are found in the literature for forms of ‘elective co-parenting’ and which can be recommended? Summary answer Current terminology lacks comprehensiveness and often contains additional (hidden) meanings, thereby jeopardizing its usability for research on contemporary family formation. We suggest a new nomenclature. What is known already There is an increase in the variation of family forms, types of parenthood roles and methods for family formation. One such way of family building has most recently been referred to as “elective co-parenting”. Not to be confused with parenting after separation, elective co-parenting typically alludes to the intentional undertaking of a shared parental project by persons who are primarily in a reproductive (and not a ‘romantic’) relationship with each other. However, many other terms and somewhat diverging concept definitions have been put forward. It seems that a fundamental conceptual framework has not yet been established. Study design, size, duration We will adhere to a tailored set of guidelines for conceptual engineering organized in five stages: (i) Identify potential attributes by collecting a representative set of definitions, (ii) Organize the potential attributes by theme and identify any necessary & sufficient or shared ones, (iii) Develop a preliminary definition of the concept, (iv) Determine what functions our concepts should serve going forward, (v) Refine the conceptual definition and improve or replace the concept. Participants/materials, setting, methods A scoping review was performed by implementing a wide-ranging search string in ProQuest. We used the following selection criteria: the article is (a) a peer-reviewed journal article, book chapter, conference paper, or report, (b) published in the last ten years, (c) written in English, that (d) proposes an explicit concept definition (also including normative meanings). Papers cited in the retrieved publications were also included if they satisfied (a), (b), (c) and (d). Main results and the role of chance After screening the available literature for academic articles that contained one or several explicit definition(s) of ‘elective co-parenting’, and that met the other selection criteria; (a), (b) and (c), key attributes mentioned in these definitions were organized in themes, i.e. necessary and/or sufficient conditions; e.g. (a) ‘Pre-conception temporality’, (b) ‘Collaborative nature’, etc. Data analysis is currently ongoing. Our aim is to put forward a new and comprehensive concept definition. In this, we will provide more clarity by making explicit all the necessary conditions (and not merely one or two as is the case in many current definitions). Furthermore, prompted by ethical considerations (e.g. ‘elective’ puts notable emphasis on free choice), we will also propose a new term for the concept of ‘elective co-parenting’; one that is more neutral and therefore more appropriate to describe the particular family building practice. The study will be completed in the forthcoming months. Limitations, reasons for caution The main challenge of this study was the construction of a suitable search strategy to find papers on a topic for which a wide range of (often contested) concepts and terminology was used. For this, several, but certainly not all (e.g. empirical research), possible strategies and data sources were explored. Wider implications of the findings This study highlights the importance of establishing clear concepts and concept definitions in the pursuit of high quality research. Providing a more appropriate concept and concept definition for what is now known as “elective co-parenting” renders further inquiry into the topic more intellectually and ethically sound. Trial registration number N/A