Background: Acquired apraxia of speech (AOS) has been shown to be responsive to behavioural intervention. Although numerous treatments for AOS have been developed, most have received limited study. Specifically, the AOS treatment evidence base is compromised by a lack of replication of treatment effects. Sound Production Treatment (SPT; Wambaugh, Kalinyak-Fliszar, West, and Doyle, 1998) has undergone more systematic examination than other AOS treatments and has been documented to result in predictable improvements in consonant production. However, SPT has not been studied with persons with severe AOS and perseverative speech behaviours. Aims: The purpose of this investigation was to examine the acquisition, response generalisation, and maintenance effects of SPT with a speaker with severe AOS, significant nonfluent aphasia, and verbal perseverations. Methods and Procedures: A single-participant, multiple baseline design across behaviours was employed to examine the effects of treatment on production of six consonants in monosyllabic words. Treatment was applied sequentially to two sets of items, with three consonants targeted in each set. A third phase of treatment entailed training of all target sounds. Follow-up probing was conducted at 10 and 15 weeks post-treatment. Outcomes and Results: Improved productions were observed for all trained items and response generalisation to untrained exemplars of trained items was positive. Across-sound generalisation was not evident. Maintenance effects were strong at 10 weeks post-treatment, but diminished considerably for most of the sounds by 15 weeks. Conclusions: Results for this speaker with severe AOS and verbal perseverations were similar to those previously reported for SPT. The decrease in performance from 10 weeks to 15 weeks indicated that changes in behaviour had not been sufficiently instantiated. Furthermore, these findings suggested that maintenance probing may need to be conducted over a considerably longer period of time than has previously been reported in the literature.