Children develop in the domains of cognition, speech and language, motor, personal skills, social skills and activities of daily living in a predictable and organised manner. Between 3000 and 9000 Australian children born in any one year may be diagnosed with global developmental delay. Paediatricians are often faced with the dilemma of ‘who’ and ‘how’ to investigate, as the yield is often considered to be low. ‘Best practice’ guidelines on the investigation of global developmental delay have been published, but the evidence available for the specific recommendations varies significantly and is based mostly on levels III and IV evidence (non-experimental descriptive studies and expert opinions). This paper discusses the current views and suggests a possible algorithm for clinical practice in Australia.