Now that the conjectures of Leedham-Green and Newman have been proved, we probe deeper into the classification of p-groups using coclass. We determine the pro-a-groups of coclass at most 3 and use these to classify the a-groups of coclass at most 3 into families. Using extensive computational evidence; we make some detailed conjectures about the structure of these families. We also conjecture that the a-groups of arbitrary fixed coclass exhibit similar behaviour.