We conceptualize and measure upward mobility over income or wealth. At the core of our exercise is the Growth Progressivity Axiom: transfers of instantaneous growth rates from relatively rich to poor individuals increases upward mobility. This axiom, along with mild auxiliary restrictions, identifies an “upward mobility kernel” with a single free parameter, in which mobility is linear in individual growth rates, with geometrically declining weights on baseline incomes. We extend this kernel to trajectories over intervals. The analysis delivers an upward mobility index that does not rely on panel data. That significantly expands our analytical scope to data-poor settings.

Putnam defines social capital as “features of social organization, such as networks, norms and social trust that facilitate coordination and cooperation ” (Putnam 1995: 67). Social networks are typically associated with social trust and with norms that promote coordination and cooperation for mutual benefit. Strong ties between individuals, infused with norms of reciprocity and trust, are often thought to help cooperation among them. They would enable these groups and society as a whole to deal smoothly and effectively with multiple social and economic issue. Other authors have noted that, in different contexts, strongly bonded groups may have adverse consequences for others (such as Portes and Landolt (1996)) or for themselves (see for instance Akerlof (1976) or Basu (1986)). Based on our earlier work on risk sharing in groups and networks (Genicot and