Abstract Background Regular monitoring of patient progress is important to assess the clinical effectiveness of an intervention. Recently, initiatives within UK child and adolescent mental health services (CAMHS) have advocated the use of session-by-session monitoring to continually evaluate the patient’s outcome throughout the course of the intervention. However, the feasibility and acceptability of such regular monitoring is unknown. Method Semi-structured qualitative interviews were conducted with clinicians ( n  = 10), administrative staff ( n  = 8) and families ( n  = 15) who participated in a feasibility study of an electronic session-by-session outcome monitoring tool, (SxS), which is based on the Strengths and Difficulties Questionnaire (SDQ). This study took place in three CAMHS clinics in Nottinghamshire. The interview transcripts were thematically analysed. Results We found clinicians accepted the need to complete outcome measures, particularly valuing those completed by the patient. However, there were some difficulties with engaging clinicians in this practice and in the training offered. Generally, patients were supportive of completing SxS in the waiting room prior to the clinic session and assistance with the process from administrative staff was seen to be a key factor. Clinicians and families found the feedback reports created from SxS to be helpful for tracking progress, facilitating communication and engagement, and as a point of reflection. The use of technology was considered positively, although some technological difficulties hindered the completion of SxS. Clinicians and families appreciated the brevity of SxS, but some were concerned that a short questionnaire could not adequately encapsulate the complexity of the patient’s issues. Conclusions The findings show the need for appropriate infrastructure, mandatory training, and support to enable an effective system of session-by-session monitoring. Our findings indicate that clinicians, administrative staff and young people and their parents/carers would support regular monitoring if the system is easy to implement, with a standard ‘clinic-wide’ adoption of the procedure, and the resulting data are clinically useful.