Background: Healthcare workers risk stress, burnout and fatigue from time pressures, insufficient workload control and ineffective support. Unaddressed, these issues can lead to the attrition of the workforce. Retention of speech and language therapists (SLTs) is an ongoing concern, but little is known about the relationship between SLT wellbeing and their workplaces. Aims: The aims of the present study were therefore to: (1) Explore the levels of job satisfaction and general wellbeing of SLTs working clinically. (2) Describe the occupational environments of SLTs working clinically. (3) Investigate the relationship between job design and wellbeing outcomes. (4) Establish whether job satisfaction and general psychosocial wellbeing levels were consistent over time. (5) Explore whether personal changes/changes to work made by participants over a 3-month period impacted their job satisfaction and/or general wellbeing. Method: All SLTs practising clinically in the UK were eligible to participate. Participants were recruited via selective sampling (advertising in Royal College of Speech and Language Therapists publications) and snowballing (using social media). A longitudinal study, using an online survey at two time points (P1 and P2), approximately 3 months apart, measured work stressors of SLTs, job satisfaction and general wellbeing, using the Speech-language Pathologist Stress Inventory, Generic Job Satisfaction Survey and General Health Questionnaire-28 (GHQ-28). Relationships between job types, wellbeing and subsequent changes were analysed using multivariate analysis of variance. Results: Of the 632 participants at P1, 98% were women, 95% were white and the average age was 38.7 years. Ninety-one percent were working in England, and 85% were organisationally employed. At P1, 53.3% of participants who completed the GHQ-28 reported anxiety, depression, somatic symptoms of stress and social dysfunction. Those in high-demand, low-control, and low-support ('Isostrain') jobs (n = 105) had the lowest job satisfaction (p < 0.001, partial [eta-squared] = 0.383) and poorest wellbeing (p < 0.001, partial [eta-squared] = 0.210). Wellbeing scores were stable from P1 to P2 (n = 295). Making 'positive personal changes' had no impact on job satisfaction, although changing jobs did (t (16) = -3.225, p < 0.01). Conclusion and Implications: Over half the participants in this study reported psychosocial ill health associated with the demands, control and support in their jobs. Psychosocial risks are embedded within work organisation, suggesting that employers and managers of SLTs consider the overall psychosocial design of jobs, with a view to improving retention. The use of a step-by-step risk assessment and intervention approach is recommended. Further research may corroborate the results and ensure better psychosocial risk management.