The problems of establishing sufficient numbers of adequately skilled mental health nurses with the motivation to work in this field over the long term are well known. Recruitment and retention remain problematic particularly in light of the ageing workforce. Nursing workloads, stress and burnout, workplace violence and aggression, for example are frequently identified as major contributors to these problems. While these factors have been identified and articulated, the relationship between them has received significantly less attention. This paper provides an overview of the relationship between these factors and subsequently emphasises the need for them to be considered collectively rather than individually. More effective and sustainable workforce planning will be facilitated through recognition of the complexity of mental health nursing rather than by artificially reducing it to component parts.