Abstract Functional communication in a typical conversation involves complex adjustments by conversation partners (interlocutors) at multiple levels of language structure. Current accounts of this center on typical interlocutors and do not provide an adequate framework for understanding how functional communication emerges in interactions involving those with communication disorders. The current proposal aims to expand existing accounts through the systematic study of communicative interaction involving persons with ALS (PALS). ALS is a degenerative neurological condition that negatively affects verbal communication. This decline in verbal ability significantly diminishes quality of life of PALS and their family. Current interventions to enhance verbal communication focus mainly on improving a speaker’s productions, but this approach is less effective in degenerative conditions such as ALS in which speakers’ abilities continue to decline in spite of intervention. In the current proposal, we aim to (a) extend current theoretical accounts to involve those with communication disorders by studying PALS and (b) explore the feasibility of clinical interventions that leverage interactions to support verbal communication in degenerative diseases like ALS. We will do so through a set of three concordant, independent aims. In Aim 1, we will study highly structured interactions involving PALS and unfamiliar interlocutors that will focus on the phonetic level. In Aim 2, we will study more naturalistic interactions to study the flexibility PALS have at other levels of language structure (e.g., syntax and pragmatics). In Aim 3, we will incorporate caregivers into structured interactions with PALS and assess the clinical feasibility of interventions based on interactions. Upon the successful completion of this project, we will obtain an improved understanding of communicative interactions involving interlocutors with communication disorders. Specifically, our findings will elucidate patterns of change that support communication success for PALS and their interlocutors. These findings will also provide an evidence base for novel interventions to support verbal communication for people with degenerative conditions.