The paper evaluates the reliability of network measurement instruments for measuring social support exchange in complete networks. The author presents and discusses the results from ten experiments, designed for analysing the reliability of five measurement scales: (1) binary, (2) 5-point categorical, (3) 5-point categorical with labels (4) line production, and (5) 11-point categorical scale as well as two measurement methods for listing alters (free recall and recognition), type of network question (original, reciprocated), and characteristics of MTMM design (time between instrument presentations). Reliability was estimated by the true score multitrait-multimethod (MTMM) approach. Meta-analyses of factors affecting the reliability and the validity of network measurement, done by Multiple Classification Analysis, show the binary scale and the first presentation of measurement instruments as the least reliable. Surprisingly, the two data collection methods (free recall and recognition) and the two types of network questions (original, reciprocated) yield equally reliable data.