The Timed Interval Categorical Observation Recorder (TICOR), a portable, battery powered microcomputer designed to automate the collection of sequential and simultaneous behavioral observations and their associated durations, was developed to overcome problems in gathering subtle interaction analysis data characterized by sequential flow of behaviors, simultaneous occurrence of several behaviors, and the duration of the behaviors. TICOR has been used in studies of teacher effectiveness, bilingual education, mental health, and physical education. Data are recorded electronically on a microcassette by pressing the appropriate keys of the 64 on the keyboard, and are later analyzed by the TICOR Data Analysis Computer (DAC) to provide summary reports of the variable frequencies, durations, and profiles of sequential and simultaneous variables. Available subject specific TICOR-DAC monitoring procedures include STUDAT, which monitors student attention to task; INSTAT, which monitors teacher instructional strategies and their relationship to teacher attention; EQUAT, which monitors teacher questioning and student attention. Many advanced interobserver reliability and data analysis procedures are available. The Microcomputer is programmable in FORTRAN, and has the capability of collecting covert responses from student response pads and analog input from autonomic responses. (Author/CMV)