Background: Patient Reported Outcome Measures (PROMs) are increasingly being used in Child and Adolescent Mental Health Services (CAMHS). The aim of this research was to explore change in standardized and idiographic outcome measures in CAMHS using naturalistic, routinely collected data. Method: We explored change in psychosocial difficulties and impact on daily life as evaluated by a broad standardized measure, the Strengths and Difficulties Questionnaire (SDQ) (Goodman, 1997, J. Child Psychol. Psychiatry, 38, 581) and progress toward goals as evaluated by a personalized idiographic measure, the Goal Based Outcomes tool (GBO) (Law, 2011, Goals and Goal Based Outcomes (GBOs): some useful information. London: CAMHS Press) in a sample of N = 137 CAMHS attenders. Results: Psychosocial difficulties and impact on daily life showed less change over the course of treatment than progress toward goals in this study. Change in psychosocial difficulties and impact on daily life were also less strongly associated with change in clinician-reported functioning and satisfaction with care at time two than change in progress toward goals. Conclusions: Findings of the present research may support previous studies in which service users and clinicians report that idiographic measures are more capable than standardized measures of capturing relevant change for individuals.