Variability and co-variation in substance use behaviors across the transition out of high school will be examined by high-intensity web-based assessment (i.e., a measurement burst design). Such high-intensity measurement is required during this stage of the life course because of the experimental nature of the transition to adulthood, including lack of permanent role commitments and exploration in various domains of life. Three specific aims will be addressed. (1) Describe and explain substance use across the transition out of high school in relation to dynamic movement into new social roles and contexts. Intensive data across the transition out of high school will extend what is known from existing long-term longitudinal data resources that monitor trends in substance use across time. (2) Examine within-person associations of drug and alcohol use with other health behaviors (i.e., sexual, eating, sleeping, physical activity behaviors) and consequences (i.e., substance use problems; difficulties in school, work, and relationships). In addition to cumulative developmental trends, behaviors within-persons and across occasions have great variability and implications for health. (3) Inform methodological designs by documenting initial response rates and investigating potential effects of repeated assessments in a web-based measurement burst design on behaviors, response patterns, and attrition. This project will provide information to support advances in survey research methodology and operations by examining: a) whether web-based surveys are appropriate measures for a diverse population of students transitioning out of high school, b) whether students can appropriately be retained across this transition in both high- and low-intensity measurement conditions, and c) how intensive measurement conditions affect both attrition and survey responses over time. Participants will complete a baseline survey in senior year of high school, and then will be surveyed with 14-day web-based diary measurement bursts three times (at 4 month intervals) to assess their experiences in school, work, family, and relationships to address Aims 1 and 2. To address Aim 3, a randomly selected half of participants will be assigned to a low measurement intensity subgroup (i.e., one follow-up survey 12 months after baseline) to serve as a control group to assess the effects of providing the intensive reports of daily behaviors on response rates and reported behaviors. This study is designed to make a substantive contribution to substance use research by documenting variability and patterns of drug use behaviors and consequences across the transition out of high school and a methodological contribution regarding the effects of repeated measurement on response.