JythonMusic is a software environment for developing interactive musical experiences and systems. It is based on jMusic, a software environment for computer-assisted composition, which was extended within the last decade into a more comprehensive framework providing composers and software developers with libraries for music making, image manipulation, building graphical user interfaces, and interacting with external devices via MIDI and OSC, among others. This environment is free and open source. It is based on Python, therefore it provides more economical syntax relative to Java- and C/C++-like languages. JythonMusic rests on top of Java, so it provides access to the complete Java API and external Javabased libraries as needed. Also, it works seamlessly with other software, such as PureData, Max/MSP, and Processing. The paper provides an overview of important JythonMusic libraries related to constructing interactive musical experiences. It demonstrates their scope and utility by summarizing several projects developed using JythonMusic, including interactive sound art installations, new interfaces for sound manipulation and spatialization, as well as various explorations on mapping among motion, gesture and music.