There is considerable evidence suggesting that a wide range of childhood and adolescent externalizing behaviors are prospectively associated with the subsequent development of alcohol use (AU) and alcohol use problems (AUPs), including several dimensions on which data have been collected within the ALSPAC study: e.g., conduct problems, temperament, personality, sensation seeking, and impulsivity. Clearly, we would not expect these various aspects of externalizing behavior to act independently, but rather to operate on AU and AUPs through a dynamic system of influences, both within and across time. For example, early temperament has been shown to influence later conduct problems, for which there are also known associations with aspects of personality, impulsivity, and sensation seeking. There is little clarity, however, regarding how mechanistic associations between these facets ultimately influence AU and AUPs in adolescence and adulthood. Prior to examining the structural nature of these relationships, we must first establish the factor structures within each of the dimensions, independently. So, for example, ALSPAC has collected information on conduct problems assessed across several points in time, and with multiple instruments (e.g., the Revised Rutter Parent Scale for Preschool Children at 42 months and repeated assessments of the Strengths and Difficulties Questionnaire at ages 6.5, 9.5, and 11.5 years). In order to assess development within conduct problems, we must first confirm that the two scales tap into the same underlying construct. Toward this end, one strategy that we propose is to identify a set of "anchor" items/behaviors that are assessed within both measures (e.g., is inconsiderate of others, steals, destroys/damages property, fights, bullies, lies/cheats). We can then subject this common set of variables to within-wave confirmatory factor analysis, allowing us to differentiate between items that yield consistent parameter estimates across time (equivalent factor loadings across assessments) and those for which associations with the underlying construct vary across time (i.e., some items may reflect behavior that is more or less indicative of conduct problems at different stages of development). Time-specific factor score estimates (FSEs) can then be derived by specifying a model which equates factor loadings across time for those items displaying factorial invariance, while freely estimating loadings at each wave of assessment for those items displaying developmental inconsistency. Moreover, we propose to implement these procedures across the different dimensions of externalizing behavior that have been conducted in ALSPAC. The resulting FSEs, which capitalize on consistency while also recognizing the potential for specific behaviors to increase/decrease in relevance across development, can then be used as the unit of measurement in models addressing the complex structural relationships between individual dimensions of behavior, general domains of risk, and alcohol-related outcomes. Accordingly, the broad goal of this set of analyses will be to characterize the measurement of, and inter-relationships between, different domains of externalizing behavior that have been assessed in ALSPAC, in order to use this information to study how different facets of externalizing behavior relate to alcohol use. We have previously had a conference call with Barbara Maughan (and Glyn Lewis) and discussed her interesting work on trajectories of conduct problems and externalizing behavior in the ALSPAC sample, so we would plan to work with her (and other interested ALSPAC collaborators) on these efforts, so as to ensure there is no duplication of effort across the projects. Since our primary interest is in understanding how externalizing behavior relates to alcohol use (with the latter being our primary outcome of interest), and her interest is in the nature of externalizing behavior itself (her primary outcome of interest), we believe that our projects will be synergistic rather than overlapping in scope.