EENDEED (Enhanced Engagement Nurtured by Determination, Efficacy, and Exchange Dimensions) is an instrument for measuring the engagement of both remote workers and traditional workplace employees. The purpose of this study was to validate the relationship between EENDEED and its three main theories, namely: 1) self-determination theory, 2) self-efficacy theory, and 3) social-exchange theory. This was done by looking at the relationships between EENDEED and three validated instruments: a) Balanced Measure of Psychological Needs (BMPN), b) General Self-Efficacy scale (GSE-6), and c) Utrecht Work Engagement Scale (UWES-9), that are based respectively on self-determination theory, self-efficacy theory, and social exchange theory. Data were collected from 600 participants in the United States through an online survey. A structural equation model (SEM) was created to ascertain the relationship between EENDEED and the three validated instruments, thus their subtending theories. Findings suggested the existence of positive significant relationships between engagement as measured by EENDEED and BMPN, SGE-6, and UWES-9. Results indicated that for every 1 standard unit increase in the employee engagement as measured by EENDEED, there was an expectation to see an increase in BMPN, GSE-6, and UWES-9 scores by .55, .85, and .82 standard points respectively. This study provided support for external validity of EENDEED and confirmed the existence of positive and significant relationships between engagement of remote employees and traditional office workers as measured by EENDEED and 1) self-determination as measured by BMPN, 2) self-efficacy as measured by SGE-6, and 3) social exchange-based engagement as measured by UWES-9.