Parents can face many new challenges in bringing up children with many now accessing the internet for general parenting support and advice. Much is known about patterns of parenting that support children’s positive development and a lot of research has demonstrated the effectiveness of parenting programmes to support parents of high challenge children. These interventions teach positive parenting skills, including relationship building, play, positive reinforcement and emotional regulation generally taught through discussion, training in observation skills and positive role modelling. The growing evidence for the effectiveness of teaching parents positive parenting strategies has demonstrated the potential of such programmes to improve the mental health and well-being of both parents and children. However, there is relatively little evidence-based information on parenting available in general. Many of the available programmes target children at-risk of developing conduct problems or families living in high-risk areas (e.g. Flying Start areas), meaning that the majority of parents do not have access to evidence-based information. Universal parenting programmes have the potential to promote positive child well-being and prevent future mental health problems. Advantages of a universal provision include (1) providing support for parents whose children do not have problems but who are concerned to parent their children in ways that provide them with the best outcomes, (2) facilitating access to evidence-based information for parents who are facing common everyday parenting challenges, but not currently in receipt of services, (3) impacting on societal norms by promoting positive parenting more widely, and (4) encouraging positive child development. The COPING parent (COnfident Parent INternet Guide) programme is a web-based universal programme that presents evidence informed parenting principles to support all parents in establishing positive relationships with children and promoting their children’s Evaluation of the COPING parent programme well being and development. This thesis reports on the development and evaluation of the programme in a randomised controlled trial with intervention and wait-list control conditions. Chapter 2 is a review of universally available parenting programmes, based on social learning theory principles, that were either offered to a universal population or included universal goals i.e. development of parenting skills and promotion of child developmental outcomes. This review highlighted the need for more research to establish the effectiveness of universal programmes on promoting positive parenting skills and child development. This leads to chapter 3, which is a review of web-based interventions for behaviour change, both behaviour in general (such as weight-loss and smoking) and parenting behaviour are included. This review highlighted the need for further evaluations of web-based parenting interventions and associated attrition challenges. Chapter 3 discusses the many challenges, which parents can face, and how these challenges can compromise parenting, child behaviour and parent-child interactions. Chapter 4 contains a brief review of interventions created using the LifeGuide software and a detailed description of the development of the COPING parent programme. Chapter 5 is a published paper (Owen & Hutchings, 2017) reporting our feasibility study that was conducted to gain user feedback from an early version of the programme. Feedback suggested modifications that included adaptations to enable the programme to be accessed by tablet users; an option to look back over previously completed chapters, the inclusion of more video examples of positive parenting and text message reminders to address engagement. Chapter 6 is the published protocol paper (Owen, Griffith & Hutchings, 2017) providing details of the methodology of the main trial. Chapter 7 is the main outcomes paper, and reports the findings from the evaluation of the programme, limitations and suggested improvements. The COPING parent web-based universal programme was effective in increasing observed praise and reducing observed indirect commands for parents who completed at least one chapter of the programme, however trial Evaluation of the COPING parent programme challenges included low engagement, high attrition at follow-up and softare challenges. The final chapter of this thesis provides a summary of the research findings and discusses implications, strengths and limitations and future directions. This was the first evaluation of the COPING parent online universal programme, an intervention for all parents of children aged 3-8 years who have an interest in learning more about positive parenting strategies. Findings from the main trial were promising and suggest that an online universal programme can significantly increase the positive parenting skills that are associated with good child outcomes for some parents. This thesis has highlighted the importance of providing all parents with the opportunity to access evicence-based support and further develop their parenting competencies in order to promote children’s development.