The present study aimes to explore the developmental changes that occur in the prospective memory and metamemory through the stages of adulthood and aging .It aimes also to explore the ability of metamemoty in its three dimensions, to predict the efficacy of prospective memory in each stage of development. The research sample consisted of (124) adults, whom their age ranged from (40-59) and (126)old age ,whom age ranged from (60-80). The battery that was used consisted of self rated scale and

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... rformance measure of prospective memory and self rated scale for metamemory . The results indicated a significant differences in self rated time and event based prospective memory, as adults outpermed old age . The results also indicated a significant differences in performed timebased prospective memory,as old age outperformed adults, and a significant differences in self rated time and event based prospective memory between females adults and males adults, as females adults outperformed males adults. With regard to metamemory ‫؛‬ old age were more aware of tasks of memory , while adults were more aware of abilities of memory ,and the changes that happen to it across age . Males adults were more aware of strategies than females adults .Finaly, metacognitive awareness of strategies predicted the efficacy of prospective memory through the stages of adulthood and aging. Key words: event -based prospective memory, time -based prospective memory,metamemory .