This report, titled "When and How to Develop Domain-Specific Languages," by M. Mernik, J. Heering, and A.M. Sloane, explores the challenges and methodologies involved in developing domain-specific languages (DSLs). DSLs are specialized languages tailored to specific application domains, offering enhanced expressiveness and ease of use compared to general-purpose programming languages. The authors identify patterns in the decision, analysis, design, and implementation phases of DSL development, extending earlier work on DSL design patterns. They also discuss domain analysis tools and language development systems that can aid in speeding up the development process. The report highlights the importance of DSLs in enabling software reuse, improving productivity, and reducing maintenance costs. Despite the benefits, DSL development is complex and requires both domain knowledge and language development expertise. The authors provide a systematic survey of factors involved in DSL development, including decision-making, domain analysis, design, and implementation. They also compare their patterns with those proposed by Spinellis and discuss the role of language development systems in facilitating the process.This report, titled "When and How to Develop Domain-Specific Languages," by M. Mernik, J. Heering, and A.M. Sloane, explores the challenges and methodologies involved in developing domain-specific languages (DSLs). DSLs are specialized languages tailored to specific application domains, offering enhanced expressiveness and ease of use compared to general-purpose programming languages. The authors identify patterns in the decision, analysis, design, and implementation phases of DSL development, extending earlier work on DSL design patterns. They also discuss domain analysis tools and language development systems that can aid in speeding up the development process. The report highlights the importance of DSLs in enabling software reuse, improving productivity, and reducing maintenance costs. Despite the benefits, DSL development is complex and requires both domain knowledge and language development expertise. The authors provide a systematic survey of factors involved in DSL development, including decision-making, domain analysis, design, and implementation. They also compare their patterns with those proposed by Spinellis and discuss the role of language development systems in facilitating the process.