User-centered design is an approach to designing technology that focuses on the needs of the user during design activities. When children are the target audience, this means designing for the needs, abilities, and expectations children have regarding technology. The key challenge, then, is how to design according to the actual needs, abilities, and expectations of children rather than the supposed needs and expectations reported by their adult representatives. A host of design approaches have been developed to support involving children since the late 1960s. While the goals of design approaches tend to be explicitly discussed, there are common themes and repeated patterns that appear in multiple design approaches. This monograph identifies the significant or recurrent themes and patterns that can be identified across methods and techniques developed for designing with children. These themes provide useful tools and common language to analyse existing and aid in creating new design approaches. The emphasis is on papers that describe work with (young) children rather than teens, and children with communication gaps caused by disability or cross-cultural work. Patterns and Themes in Designing with Children will be of use for designers working with children in participatory design and co-design activities. Awareness of the themes and patterns discussed in this monograph will allow designers selecting existing design approaches, or creating their own, to better understand and compare existing design approaches.