If you had a dependable method for determining the healthiest and most viable conceptus from a cohort of growing preembryos, replacing more than a single one in order to achieve good pregnancy rates would be moot. Sometime in the not-so-distant future, this may be a reality. Taking a step towards that future, An Atlas of Human Blastocysts vividly illustrates the typical and atypical morphology of mammalian blastocysts. The atlas demonstrates that extended culture of blastocysts is now achieveable in the laboratory and points us toward the day when it will be possible to choose between a number of healthy hatched blastocysts.