1. A recent comprehensive definition

In response to the lack of uniformity and guidelines regarding definitions, Fleuren et al. (2020) ^[1] propose a novel definition rooted in a fundamental consideration of the elements 'sustainable'  and 'employability'. Employability here refers to an individual's 'ability of being employed' and should thus capture an individual’s capacity to function at work, but also on the labor market. As such, it should consist of several indicators that describe an individual's functioning comprehensively. Sustainable then refers to something being 'able to be used without being completely used up'. Effectively, this can be further translated to the use of a resource over time, without the utility value of that resource being negatively–and preferably positively–affected by its use.

These basic definitions in combination with indicators from the scientific literature result in the following definition: “Sustainable employability means that an individual’s ability to function at work and in the labor market, or their ‘employability’, is not negatively, and preferably positively, affected by that individual’s employment over time. This ability can be captured meaningfully as a combination of nine indicators (i.e., perceived health status, work ability, need for recovery, fatigue, job satisfaction, motivation to work, perceived employability, skill-gap, and job performance) that collectively describe how well an individual can be employed at different points throughout the working life."^[1]

2. Other definitions

As discussed, several other of sustainable employability exist as well. However, as discussed by Fleuren et al. (2020), these definitions typically insufficiently recognize the inherently longitudinal nature of the contruct, combine individual and contextual aspects in their conceptualization, and/or miss important aspects of functioning. This is not to say that the aforementioned definition of sustainable employability is perfect; the exact indicators chosen for functioning might require expansion or updating as insights into what functioning at work encompasses in the future cumulate. 

3. The essence of sustainable employability research

Regardless of the exact definition chosen, at its core the research so far seems to suggest that studies on sustainable employability should include several aspects of functioning. That is, functioning at work is a complex multidimensional socially constructed concept. Moreover, time (although previously insufficiently acknowledged) is an essential element as well. Quality studies on sustainable employability should therefore encompass multiple measurement occassions of individual's occupational functioning broadly. That way, the sustainability aspect can be captured by monitoring change in functioning over time.^[1]

Additionally, it is essential to connect sustainable employability to aspects of the working environment or, more broadly, the employment context of individuals. The purpose of studies on sustainable employability is namely to identify aspects of employment (i.e., the work itself, the work context, and the broader societal context) that enable individuals to continue labor participation on the long term. That is, sustainable employability research mainly emerged in response to raises in the retirement age, following pressure on retirement systems (particularly in Northern Europe) due to population aging. 

Finally, sustainable emploayability research has initially focused on employees of older age. However, it is important that this focus is extended to employees of all ages, but also non-employed individuals. That is, if the factors that hamper long term labor participation are to be understood fully, individuals need to be studied throughout their working lives to also incorporate early exposure factors. Additionally, younger individuals may also encounter employment conditions that result in early labor market withdrawal that could potentially result in long-term damage to their employability. Moreover, to truly maximize labor participation in the entire population, employment needs to be inclusive and also enable people who are currently not able but willing to work to also obtain employment. 

4. The extended employability paradox

A key issue relating to the topic of employability in the more traditional sense (i.e., labor market attractiveness without the sustainability component connected to it) is the responsibility for employability. Different viewpoints suggest different stakeholders being responsible for an individual's employability: the individual employees themselves, the employer, society, or any combinations thereof. This discussion is rooted in the idea of the employability paradox; the idea that investing in employees' employability could be investments lost for the gain of other competing employers. Consequently, some organizations prefer to put the responsibility for employability on individual employees. This discussion extends to sustainable employability, where it is argued that employers would not necessarily have a caring responsibility for their employees. However, the inherent connection between sustainable employability and factors in the employment context that the employer controls, suggest a responsibility on the employer side is undeniable.