Nursing home residents with dementia are commonly prescribed antipsychotics despite the associated increased risk of harms. Interventions to optimize prescribing practice have been found to be effective in the short term, but there is a lack of evidence to support sustainability of effects, along with a lack of theory, public involvement, and transparency in the intervention development process. Using theory has been advocated as a means of improving intervention sustainability. The aim of this study was, therefore, to identify behavior change techniques (BCTs) for inclusion in a complex intervention targeting antipsychotic prescribing to nursing home residents with dementia. A comprehensive approach to identifying a long list of all potential BCTs from three different sources was undertaken. The most appropriate BCTs were then selected through a two-round Delphi consensus survey with a broad range of experts (n = 18 panelists). Advisory groups of people with dementia, family carers, and professional stakeholders provided feedback on the final BCTs included. After two Delphi survey rounds, agreement was reached on 22 BCTs. Further refinement of the selected BCTs based on advisory group and panelists' feedback, along with use of the APEASE criteria (Affordability, Practicability, Effectiveness, Acceptability, Side effects/safety, and Equity) resulted in a final list of 16 BCTs. The next step in intervention development will be to identify the most appropriate mode of delivery of the 16 BCTs identified for inclusion. The study provides a case example of a systematic approach to incorporating evidence with stakeholder views in the identification of appropriate BCTs.