The persistent disparity in wages across different professions has long been a central focus of labor economics. Why does a software engineer typically earn more than a retail clerk, even when accounting for differences in education, experience, and individual talent? A new working paper, released in October 2026 under the identifier 35929 by the National Bureau of Economic Research (DOI: 10.3386/w35929), offers a fresh perspective on this phenomenon. By conceptualizing the labor market as an “occupational ladder,” researchers have developed a formal decomposition to analyze how movement between roles dictates both the trajectory of average wage growth and the widening of income inequality over the course of an individual’s working life.
The research provides a nuanced look at the mechanics of career progression. It suggests that the labor market is not merely a collection of isolated roles, but a structured hierarchy where occupations can be ranked by their compensation potential. As workers accumulate experience, they do not simply become more productive within their existing roles; they often shift their employment toward these higher-paying rungs. This structural movement, the researchers argue, is a fundamental, albeit misunderstood, component of the modern economy.
The Dynamics of Occupational Mobility and Wage Growth
The first major finding of the study concerns the influence of occupational shifts on the overall growth of wages during a worker’s career. The authors observe a distinct trend: as employees gain tenure and professional maturity, the aggregate distribution of employment consistently tilts toward higher-paying occupations. This migration is most pronounced in the early stages of a career, suggesting that the "entry-level" phase is characterized by a high degree of volatility as individuals seek to position themselves on more lucrative rungs of the occupational ladder.
While this upward mobility is significant, the study notes that its contribution to total life-cycle wage growth is modest. This is an important distinction for labor market analysts. While moving from a lower-paying sector to a higher-paying one undoubtedly boosts an individual’s paycheck, it is not the sole, nor perhaps even the primary, driver of the steady wage increases seen as workers age. Instead, this occupational ladder effect acts as a foundational, steady influence, providing a consistent tailwind during the formative years of a professional life, but eventually giving way to other factors as a worker reaches mid-career stability.
The Myth of Occupational Dispersion
One of the most counterintuitive findings of the research addresses the relationship between occupational mobility and wage inequality. It is a common assumption in labor economics that as workers sort themselves into different roles, the resulting stratification contributes to the "fanning out" of wages—a term used to describe how the gap between the highest and lowest earners grows as they get older.
However, the data presented in this working paper tells a different story. The researchers found that the upward movement of the employment distribution across occupations is not accompanied by an increase in wage dispersion within those occupations. In other words, the act of moving up the occupational ladder does not inherently widen the income gap between individuals. This suggests that the ladder itself is a relatively uniform mechanism. While workers are indeed shifting into better-paying categories, they are not doing so in a way that creates extreme new pockets of inequality within those specific fields. The ladder, while providing a path for advancement, does not directly drive the divergence in lifetime earnings that is so often observed in modern economies.
The Role of Relative Position and Career Maturation
The third and perhaps most critical finding of the study involves the covariance between an individual’s position within a specific occupation—often referred to as the “job ladder”—and their position on the broader occupational ladder.
In the early stages of a career, there is a marked disconnect between a worker’s placement and their compensation. The study finds that young workers who are theoretically well-positioned on the occupational ladder—meaning they have secured roles in high-paying sectors—often earn wages that are significantly below the average for those specific occupations. This is likely due to the "entry-level" penalty, where the prestige or potential of a field does not immediately translate into high cash compensation for the inexperienced. At this stage, the worker is still "earning their stripes," and their relative wage is suppressed by a lack of firm-specific or role-specific experience.
However, the narrative shifts dramatically by mid-career. The researchers discovered that as workers reach their middle years, the relationship between their internal position within an occupation and their occupation’s rank on the general ladder begins to decouple. By this stage, a worker’s relative wage within their chosen field no longer depends heavily on the specific occupational category they occupy. Instead, the individual’s internal trajectory—their own personal "job ladder" success—becomes the primary determinant of their pay.
This evolution is identified as a major contributor to the fanning out of wages over the course of a career. It is not necessarily the occupation itself that creates the widening gap in earnings between high and low earners at the age of 45 or 50; rather, it is the cumulative effect of how individuals have navigated their specific job roles over time. The "fanning out" occurs because the internal variation in success within any given occupation becomes much more pronounced as workers mature.
Implications for Labor Market Theory
The implications of this research are significant for those studying labor market dynamics and economic inequality. By distinguishing between the “occupational ladder” (the rank of the field) and the “job ladder” (the relative position of the individual within that field), the authors provide a clearer framework for understanding how careers unfold.
The findings suggest that policies aimed at reducing inequality might need to look beyond simply pushing workers into "better" occupations. If the primary driver of late-career wage inequality is the variation in how individuals perform and advance within their chosen roles—rather than the initial choice of occupation—then interventions might be more effective if they focus on mechanisms that facilitate internal advancement and skill accumulation within sectors.
Furthermore, the study highlights the importance of the early-career transition. Because early-career workers are often placed in high-potential occupations but receive lower-than-average wages, there is a clear period of "investment" during which the benefits of being on a high-paying ladder are not yet realized. Understanding how long this period lasts and what factors help workers transition from "well-positioned but underpaid" to "well-positioned and highly paid" is essential for a complete picture of lifetime earnings.
As the economy continues to evolve, with shifting demands for skills and the rise of new occupational categories, the concept of the occupational ladder remains a vital tool for analysis. This working paper does not propose that the ladder is a static or unchanging structure; rather, it provides a mathematical and conceptual decomposition that allows researchers to isolate the effects of occupational shifts from the effects of individual career progression.
In sum, the study by the authors of Working Paper 35929 challenges some of the simpler narratives surrounding wage growth. It replaces the idea that upward mobility between jobs is the sole engine of rising inequality with a more complex reality: a world where the occupational structure provides the stage, but the individual’s path through their specific job—and the maturation of their role within that job—is what truly defines the wide spectrum of economic outcomes in later life. As scholars and policymakers continue to grapple with the complexities of wage distribution, this research offers a foundational piece of evidence that the path to higher earnings is paved with both the choice of profession and the individual performance within it.
