To ensure that a software system accurately reflects the business domain that it models, the system needs to enforce the business rules (constraints and derivation rules) that apply to that domain. From a conceptual modeling perspective, many application domains involve constraints over one or more conceptual schema paths that include one or more conceptual joins (where the same conceptual object plays roles in two relationships). Popular information modeling approaches typically provide only weak support for such conceptual join constraints. This chapter contrasts how these join constraints are catered for in object-role modeling (ORM), the Unified Modeling Language (UML), the Object-oriented Systems Model (OSM), and some popular versions of entity-relationship (ER) modeling. Three main problems for rich support for join constraints are identified: disambiguation of schema paths, disambiguation of join types, and mapping of join constraints to implementation code. To address these problems, some notational, metamodel, and mapping extensions are proposed.