Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) does not feature a diagnosis for infant depression, chronic maternal depression effects may appear as early as the prenatal period. Because most chronically depressed women are unwilling to take medications during pregnancy, psychology is challenged to find alternative preventive treatments. This literature also highlights the importance of genetic studies including adoption and twin research to assess potential genetically mediated risk factors for newborn depression.Whereas about 10% of nonrisk community samples experience clinical depression in the postpartum period, in at least one sample less than 2% of women experienced depression continuing past 6 months, and 80% of them recovered relatively quickly without treatment and without significantly affecting their infants' development (Campbell & Cohn, 1997). However, in communities with other risk factors such as poverty, significant numbers of women are chronically depressed (Field, 1995). For this group, maternal depression appears to affect prenatal, neonatal, and infant development.The purpose of this chapter is to review studies on this high-risk group including early intervention studies that may help inform clinicians' referrals. Most of the studies on this high-risk population were conducted by our group and therefore are presented in detail. However, studies from other labs are also briefly reviewed whenever relevant or if they served as models for our studies. In most of these studies the mothers were chronically depressed (dysthymic) as well as having other risk factors including low socioeconomic status (SES). In some studies the mothers were adolescent, another notable risk factor for maternal unavailability to infants. These risk factors are potential confounds. However, the depressed and nondepressed mothers came from the same SES and age groups, so depression was an additional factor for the group labeled depressed and seemingly the only way in which the depressed and nondepressed groups differed.In most of the studies reviewed, depression was defined as protracted state of low mood or dysthymia, typically determined by the Beck Depression Inventory (BDI; Beck et al., 1961) or Center for Epidemiological Studies Depression Scale (CES-D; Radloff, 1977) combined with a diagnostic interview (often the Diagnostic Interview Survey [DISC]). Although these measures have been noted to be significantly correlated (Wilcox, Field, Prodromidis, & Scafidi, 1996), more mothers have been classified as depressed on the basis of the BDI or CES-D alone and not the DISC, which suggests that combining one of these with the diagnostic interview yields false positives. Differential diagnosis is one of the primary methodological difficulties conducting research with this population. Other problems include noncompliance with the treatment and the research assessment process, which probably relates to those other risk factors including poverty, minority status, lack of educa...