Organisational effectiveness outlines definitions, differences between effectiveness and efficiency, importance of measuring effectiveness, and theories of effectiveness. Effectiveness is defined as an organisation achieving its goals using resources efficiently. Effectiveness reflects external goals achieved, while efficiency means internal cost to achieve goals. Theories include goal approaches measuring goal achievement, strategic constituencies approach considering environmental transactions, and behavioural approach assessing goal integration of individuals and the organisation. High integration leads to individual goals aligning with organisational goals and highest effectiveness.