Purpose: This study aimed to investigate whether a morpho-phonological intervention that used phonologically and morphologically complex target words targeted in a combination of speech and language intervention strategies resulted in improvements in speech and language measures for a child with co-occurring speech and language difficulties. The study also aimed to investigate the intervention's feasibility and whether the approach lent itself to clinician- friendly administration.

Method: The study utilised a single-case design. The participant was aged four years eleven months and presented with a mild phonological disorder and queried diagnosis of developmental language disorder as measured by the Diagnostic Evaluation of Articulation and Phonology (DEAP) and Clinical Evaluation of Language Fundamentals-Preschool 2 (CELF-P2). At the beginning of the study, the participant could not mark past tense –ed and third-person singular –s words or produce word-final /v/ and word-final /sh/. The participant received 13 intervention sessions that targeted his productions of past tense –ed in words that ended in word-final consonants or cluster /sht/, and third-person singular –s in word-final consonants or cluster /vz/ through minimal pairs, focused language stimulation, and shared story interventions. The researcher conducted a subjective feasibility analysis.

Results: The participant improved his ability to mark third person singular –s but had no change in his ability to mark past tense –ed. The participant improved his ability to produce /sht/ in word imitations and spontaneous phrases but had variable results for his productions of /sht/ in spontaneous words and all productions of /vz/. The researcher identified facilitators and barriers to the intervention project's administration and provided suggestions for improving future studies' intervention procedures.

Conclusion: This was the first study investigating the effectiveness of selecting morphologically and phonologically complex target words and administering them in a morpho-phonological intervention within the same session. This was also the first feasibility study of a morpho-phonological intervention for children with co-occurring speech and language difficulties. The results show promise that morpho-phonological intervention methods could improve the speech and language abilities in children with co-occurring speech and language difficulties.