Psychologists know well that understanding and predicting human behavior are incredibly difficult. Likewise, neuroscientists are acutely aware of how difficult it is to explain how behavior is implemented by neural mechanisms. One tantalizing possibility is that tackling both of these challenges simultaneously may be more tractable than addressing each separately at its own level of analysis. Although this ambitious and integrative path may seem fantastical, if constraints and relationships exist across measures, then this enterprise has hope. To make this hope a reality requires powerful and transparent methods to link measures across levels...