Outside catering involves preparing and serving food at a location away from the business. The outcome of outside catering is important to caterers both as a marketing tool and in enhancing customer satisfaction. There are many factors that determine the outcome of outside catering which this study aimed to establish. The objective of this study was to examine the contribution of human, physical and natural factors on the outcome of outside catering as well as to identify the indicators that can be used to measure the outcome of outside catering. The study employed descriptive survey research design. The target population was 150 caterers in Nairobi in Kenya. The sample size comprised 120 outside caterers. Purposive and snowball sampling techniques were used to identify the respondents. Questionnaires were used to collect data. Data was analysed using descriptive statistics and presented in the form of frequency tables, percentages and graphs. The results showed that human, physical and natural factors all determine the outcome of outside catering. The findings may benefit outside caterers in understanding and hence being careful on factors that affect the outcome of outside catering. In addition caterers may use the indicators that measure outcome of outside catering to improve or know the status of their work. Keywords: Human factors, Natural factors, Outcome, Outside catering, Physical factor