Project Abstract Aphasia and acquired apraxia of speech (AOS) are neurogenic disorders of language and motor speech, respectively. Individually, and in combination, these disorders can significantly disrupt communication. These disorders commonly co-occur (Duffy, 2007); in particular, AOS very rarely occurs without aphasia. Despite the likelihood that persons with both AOS and aphasia will require treatment for both conditions, there has been limited research concerning treatments that may positively impact language and speech symptoms. The purpose of the proposed research is to further develop and examine the effects of a novel behavioral treatment that targets aphasia and acquired apraxia of speech (AOS) simultaneously. This treatment, Combined Aphasia and Apraxia of Speech Treatment (CAAST), combines therapy techniques from an established aphasia treatment (i.e., Response Elaboration Training; Kearns, 1985) and a well-studied AOS treatment (i.e., Sound Production Treatment; Wambaugh et al., 1998). An initial investigation of the effects of CAAST is currently being completed with four persons with chronic aphasia and AOS. Preliminary findings are promising in that substantial improvements in production of correct information units (CIUs; Nicholas & Brookshire, 1993) have been found along with improvements in sound production. A primary purpose of the proposed research is to examine outcomes of this treatment beyond the basic measures currently being utilized. An additional purpose of the planned research is to develop/evaluate speech/language measures for use with this treatment. Three investigations are planned to advance the development of CAAST. The first investigation will utilize recently collected CAAST probe data in the form of narrative discourse samples. The purpose of the investigation is to evaluate changes in language production beyond CIUs. Probes from baseline, end of treatment phases, and follow-up will be examined in terms of mean length of utterance (MLU), phrase and sentence production, lexical form class composition, and lexical diversity and novelty. The goal of the second investigation is to begin development of appropriate speech production outcome measures for use with CAAST (and AOS treatments in general). The planned study is designed to examine the effects of repeated sampling (i.e., test-retest) on the following speech production measures with a group of 30 participants with chronic AOS and aphasia: total word and sentence durations, number of fluent utterances, and percent consonants correct. The third planned investigation will be a systematic replication of the on-going CAAST study. CAAST will be administered to four additional persons with aphasia and AOS with outcome measures derived from the first two planned investigations. The products of the proposed research will be a refined version of CAAST with appropriate, reliable speech and language outcome measures; the treatment and accompanying outcome measures are expected to have clinical and research utility.