How do contemporary fertility ideals, desires, and intentions relate to contemporary low fertility? At the empirical level the answer is straightforward: observed fertility is well below the levels of ideal family size and also usually well below respondents' desires and intentions. In fact, below-replacement fertility in many countries would disappear if respondents' fertility intentions were realized (Bongaarts 2001(Bongaarts , 2002Goldstein, Lutz, and Testa 2003).At the conceptual level, all behavioral models of contemporary low fertility feature choice: individuals choose to have children (Thomson and Brandreth 1995). Thus fertility intentions, if not ideals, hold the promise that actual fertility could mirror intentions over the long run, thus bringing observed fertility closer to replacement. Consistent with this view, Bongaarts (2002) argues that a substantial part of the discrepancy between aggregate fertility intentions and contemporary fertility levels can be accounted for by timing shifts, specifically the postponement of childbearing to later ages. Once this postponement abates, as it eventually must, 1 intentions and current behavior will be more similar. In addition, frustrated demand for children could encourage institutional adjustments that would allow childbearing to correspond to levels desired by women and couples, again raising fertility to levels that approximate intentions.Expressing an alternative view, Goldstein, Lutz, and Testa (2003) report that Germanspeaking areas of Europe now show levels of ideal and expected family size well below replacement levels (i.e., less than two children per woman), a pattern they suggest portends a permanent shift to sub-replacement fertility. They argue that the previous disjuncture between intentions and behavior in German-speaking counties, now evident in many other countries as well, represents "cultural lag." Specifically, women and couples act in accordance with contemporary antinatalist constraints and have few children, but continue for a period (a time lag) to express the prevailing cultural imperatives to be parents and to have at least two children. Younger cohorts, once they have lived much of their lives in a low-fertility setting, adopt the status quo as an expectation and thus express intentions (and ideals) that more closely correspond to contemporary behavior. Goldstein et al. (2003) hypothesize that fertility intentions and ideals in Italy, Spain, and elsewhere will soon decline further, creating greater symmetry between subreplacement fertility and subreplacement ideals and expectations. The suggestion that aggregate shifts in intentions can follow rather than precede behavioral shifts is not new (see Lee 1980;Westoff and Ryder 1977;Morgan 1981Morgan , 1982.Finally, Demeny (2003) argues that a wide gap between expressed preferences and behavior can persist indefinitely. Even if such preferences for a particular number of children are Direct all correspondence to S. Philip Morgan, Department of Sociology and Center for Demographic Studie...