This thesis presents research in the area the area of End-User Development (EUD). The first studies in EUD have emerged as an attempt to help end users achieve specific goals of personalization and customization of interfaces and systems, primarily for their own benefit. As needs evolve, end users have to know and often master more complex computing concepts and practices. In this context, there have been a growing number of initiatives to encourage, teach and support users in programming and thinking computationally. In general, much emphasis is given to problem solving, logical reasoning and other common computer scientists skills. However, supported by Semiotic Engineering, a semiotics-based theory that describes human-computer interaction as communication between designers and users, we believe that interactive computer systems are communication artifacts: that the person who creates the system sends various messages, with particular characteristics to the person who uses it. In this thesis, we present an extensive study in which end users, acting as designers, create computational artifacts for communication purposes. Research has shown that the participants took programming and other development activities not as end in themselves but as a means to build their messages. We discuss how the change in perspective (from problem-solving to communication) reveals a range of underexplored phenomena, such as self-expression of the designers and the pragmatics of interaction languages they build. Another contribution of this thesis is an extension to Semiotic Engineering, named EUME – End-User Semiotic Engineering, a new way to look at Semiotic Engineering, in the perspective of end users acting as designers.