Family economic mobility has been a policy concern for decades, with interest heating up further since the 1990s. Using data that tracks individual families’ incomes during overlapping 10-year periods from 1978 through 2014, this paper investigates the relationships of factors—family characteristics and macro influences—to intragenerational mobility and whether the importance of those factors has changed over time. Family characteristics include both levels of work behavior and family structure and within-period changes in those factors, as well as time-invariant characteristics of the family head, such as race. Macro factors include indicators of GDP growth and inflation during each 10-year period. The positions families occupy in the income distribution and the degree to which they are stuck or able to move up (or slide down) over time are critical determinants of their current well-being and their children’s prospects.