Background: There is strong public support for acute hospital services to move to genuine 7-day models, including access to multidisciplinary team assessment. This study aimed to identify factors that might enable an effective and cost-effective weekend allied health services on acute hospital wards. Methods: This qualitative study included 22 focus groups within acute wards with a weekend allied health service and 11 telephone interviews with weekend service providers. Data were collected from 210 hospital team members, including 17 medical, 97 nursing, and 96 allied health professionals from two Australian tertiary public hospitals. All were recorded and imported into nVivo 10 for analysis. Thematic analysis methods were used to develop a coding framework from the data and to identify emerging themes. Results: Key themes identified were separated into issues perceived as being enablers or barriers to the effective or cost-effective delivery of weekend allied health services. Perceived enablers of effectiveness and cost-effectiveness included prioritizing interventions that prevent decline, the right person delivering the right service, improved access to the patient's family, and ability to impact patient flow. Perceived barriers were employment of inexperienced weekend staff, insufficient investment to see tangible benefit, inefficiencies related to double-handling, unnecessary interventions and/or inappropriate referrals, and difficulty recruiting and retaining skilled staff. Conclusions: Suggestions for ensuring effective and cost effective weekend allied health care models include minimization of task duplication and targeting interventions so that the right patients receive the right interventions at the right time. Further research into the effectiveness and cost effectiveness of these services should factor in hidden costs, including those associated with managing the service.