The Monitoring the Future (MTF) study monitors historical and developmental changes in substance use prevalence among key subgroups of the general U.S. adolescent and adult population. The current study first devised and evaluated a cohort-specific pooled analysis weighing procedure for the MTF panel study that weighted back to the initial 12th grade samples. Following this, the cohort-specific weights were updated to age-specific weights in order to provide increased flexibility for a wide range of model specifications and to avoid the need to re-calculate a first half-sample respondent's final weight at a particular wave after the full cohort had completed that wave. The cohort-specific pooled analysis weights appear to result in an overall improvement in the degree to which the sociodemographic distributions of the initial 12th grade samples are retained, as well as likely producing slightly improved substance use estimates due to accounting for historical variation in panel sample selection and attrition over time. The updated age-specific pooled analysis weights continued to provide the benefits associated with the cohort-specific weights, but also brought increased flexibility for modeling both cohort- and age-specific research questions, and allowed all respondents' weights at each specific age to remain fixed across time.