Recently there have been proposals to change the way we define families for the purpose of measuring poverty. This paper used the 1990 and 1992 SIPP to examine several of the practical and conceptual issues of changing the definition of "family." This research found that the poverty rate for 1990 was not greatly affected by expanding the "family" for poverty calculations to include persons with nonfamily household relationships, although some population subgroups -- including single-parent families - were more affected. If the "family" definition were changed, many currently-available surveys would provide an inaccurate picture of poverty because they measure living arrangements at a single point in time, rather than longitudinally. Finally, the main rationale for expanding the "family" definition -- that persons in cohabiting and other nonfamily household relationships are likely to share resources -- was not given strong support in this research. Income from persons in nonfamily household roles was found to have contribute slightly less to helping other household members avoid financial hardship, implying that they tend to keep more of this income to themselves.