The acknowledgement that educational achievement is highly dependent on successful reading development has led to extensive research on its underlying factors. A strong argument has been made for a causal relationship between reading and phoneme awareness; similarly, causal relations have been suggested for reading with short-term memory and rhyme awareness alike. Here a meta-analysis is presented that seeks to determine spuriousness in these factors' relationships with reading by examining each factor's unique predictive value. The results show that phoneme awareness is the strongest unique predictor. Since the meta-analysis is based on concurrent data, it is unsuited to enlighten time-order relationships, but longitudinal and experimental studies both support the notion of a causal relationship between phoneme awareness and reading, in contrast to rhyme awareness and verbal short-term memory. (Contains 3 tables.)