Studies that have examined whole-school interventions that target conceptual knowledge reveal characteristics that are important in the delivery of a deep processing approach to word learning. These consist of explicit instruction, play, and multi-sensory experiences that are situated within and repeated across varied contexts. Word Aware (WA) is an example of a vocabulary intervention that incorporates such features. This study examined the effectiveness of the Early Years version of the WA programme in supporting the development of vocabulary knowledge in a sample of 92 children comparing them to a control group of 31 children who received usual teaching. Student speech and language therapists supported the testing and delivery of a 10-week intervention as part of their clinical placement and were interviewed along with the teachers on their perceptions of the intervention and their experiences collaborating with staff to support the whole school delivery of the programme. Informal and standardised assessment scores of receptive vocabulary showed no significant difference in the overall improvement between both groups despite finding significant improvement within each group on words targeted for intervention. Qualitative thematic analysis revealed positive observations of child engagement with aspects of the programme that aimed to promote a deep processing of word meaning. Students reported an increased sense of confidence in their ability to collaborate with teaching staff and in their willingness to engage in research as part of their clinical practice. The ceiling effects reported in the outcome measures of both the intervention and control group suggest that the WA programme may be better suited to a sample of younger-aged children. The study provides original insight into the student experience of working in a whole-class environment whilst conducting practice-based research as part of clinical placement. The methodological limitations of this study are discussed along with suggestions for future research.