1172 highest when the gender of the parent matched the gender of the adolescent; the effect of parent gender, however, was signiﬁcant for daughters but not for sons. As with previous research (e.g., Swain et al. 2006), the greatest number of topics discussed was between mothers and daughters, and the fewest was between fathers and daughters. Contrary to our expectations, none of the socio-demographic variables had an incremental effect on sexual communication once the primary demographic variables were taken into account. As hypothesized, greater parent-reported levels of comfort and knowledge predicted greater number of topics discussed, and the presence of sexual communication dif- ﬁculties predicted lower number of topics discussed, beyond the effect of demographic variables. This ﬁnding is consistent with previous research indicating the predictive power of parental comfort and knowledge in sexual com- munication between parents and their adolescents (e.g., Byers et al. 2008). Of the various types of difﬁculties reported by the 70% of the parents reporting sexual communication difﬁculties, age or developmental issues were the most common among both mothers and fathers of preadolescents. Although many parents might have beliefs or feelings about which topics are appropriate to discuss with their adolescents and at what age or developmental level to discuss them, these commonly reported age or develop- mental difﬁculties among the parents of preadolescents in our study might be addressed through parent education and support. Professional organizations recommend that children begin to be exposed to age-appropriate compre- hensive sexuality education topics as early as age 5 years (e.g., National Guidelines Task Force 2004). For parents who experience age or developmental difﬁculties in talking with their preadolescents about sex, guidance on which topics are developmentally appropriate at different ages and developmental levels might be especially valuable. The strong inﬂuence of perceived comfort and knowledge, combined with the independent role of difﬁ- culties experienced, reinforces the notion that sexual communication between parents and their adolescents can be universally challenging. Parents of both genders, all ages, and all socio-demographic characteristics might beneﬁt from guidance on strategies for initiating sexual communication with their adolescents, developmental appropriateness of speciﬁc topics, and ways to increase their knowledge and improve their comfort. Parents may also beneﬁt from understanding the important role they play in their children’s early and ongoing sexual sociali- zation and how this socialization interacts with the sex education most adolescents receive in school (Shtarkshall et al. 2007). 123 J Youth Adolescence (2010) 39:1164–1174 Parents begin inﬂuencing their children’s sexual devel- opment through sexual socialization before they begin proactively discussing sexual topics with them, by verbally and nonverbally conveying their standards regarding respect for others, affection, attitudes toward nudity, and so forth (Lefkowitz and Stoppa 2006; Shtarkshall et al. 2007). At the same time, sexual communication is more than the explicit discussion of sexual intercourse; it also encom- passes discussion of nonsexual relationships, respect, sex- ual pleasure, decision making, and many other topics. The extent of sexual communication should increase and the topics covered should evolve as children age and develop, beginning around 5 years of age and continuing through young adulthood. With increasing sexual communication, various challenges arise for parents, often tied to their less- than-optimal knowledge and comfort levels, including issues about what is appropriate to cover at what age. These challenges can sabotage their communications with and ultimately the healthy sexual development of their children. Education and support should be widely available for parents to help them become more effective sexual communicators. We note several limitations associated with this research. In taking advantage of the efﬁciency, power, and generalizability of a large, representative, statewide telephone survey, we collected the open-ended responses with a minimum of probing and follow-up questioning. Self-reported difﬁculties in talking with adolescents about sex and relationships might not provide a complete and unbiased account of the nuances of parent–adolescent sexual communication. In-depth questioning and probing about these topics with a smaller representative sample might provide additional useful information and insights. Of additional note is that our study examined only par- ents’ perceptions of parent–adolescent sexual communi- cation, and research evidence suggests that parents and their children often have different perceptions of fre- quency and extent of sexual communication (see DiIorio et al. 2003). Moreover, although the six sex education topics we used in our study are representative of the harm-reduction focus of mainstream approaches to sex education, including positive sexuality topics as part of the list of topics discussed would have added value to our scale of number of topics discussed. A further caveat is that many languages are spoken by California parents, whereas resource constraints limited our data collection to English and Spanish languages only. Thus the results reported here are not precisely representative of the full population of households with adolescents in California, and speciﬁcally, they may underrepresent non-English- speaking Asian American parents. Yet, much research of this type is conducted only in English, and the advantage of our study is that we were able to include the one-third