Entrepreneur in Residence is a kind of position in Venture Capital firms that is usually temporary and not formal. This is when an institution brings in an entrepreneur, who is usually in the process of starting or expanding his/her new company.
In the Venture Capital firm the entrepreneur is funded to work with some of the investment team of the company as well as being exposed to business-building processes, where he/she can assist the firm with any existing portfolio. In addition he/she is expected to help the company evaluate new potential investments, especially if it is an area of the E.I.R's experience. On the other hand, the company usually benefits from this by getting significant access to the new company started by the E.I.R. This is due to the fact that the company gets to, usually, be the first investor in E.I.R's new company, giving them a chance to influence some company decisions.