The Multiple Option Observation System for Experimental Studies (MOOSES) is a flexible data collection and analysis package for applied behavioral research that addresses the needs of researchers interested in live coding of observational data. MOOSES allows the researcher to design a coding system for a particular research question. General types of data that can be collected and analyzed include mutually exclusive events, toggles, and interval data. An extensive set of analyses is available, including: (1) frequency and duration; (2) interobserver agreement; (3) states within toggles; (4) sequential frequency analysis; and (5) visual analysis. Hardware requirements, program operation, and a new PROCODER compatible version are described. (SLD)