- Object Relations Test
- Object Relations Theory
- objective
- observation
- observer bias
- occupation
- occupational career
- occupational classification
- occupational community
- occupational mobility
- occupational prestige
- occupational segregation
- occupational socialization
- occupational structure
- odds ratio
- Oedipal stage
- official statistics
- Ogburn, William Fielding
- oligarchy
- oligopoly
- ontology
- open groups
- open response
- open societies and closed societies
- operant conditioning or learning
- operational definition
- operational model
- opinion polls
- opportunity structure
- optimal matching
