The Collaborative International Dictionary of English v.0.48:

Carefulness \Care"ful*ness\, n.
   Quality or state of being careful.
   [1913 Webster]

WordNet (r) 3.0 (2006):

carefulness
    n 1: the trait of being cautious; being attentive to possible
         danger; "a man of caution" [syn: caution, cautiousness,
         carefulness] [ant: incaution, incautiousness]
    2: the quality of being careful and painstaking; "I admired the
       carefulness of his work" [ant: carelessness, sloppiness]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "carefulness":
   austerity, austerity program, calculation, canniness, care,
   careful consideration, caution, cautiousness, chariness,
   circumspection, concern, consciousness, deliberate stages,
   deliberateness, deliberation, discretion, economic planning,
   economicalness, economy, economy of means, false economy,
   forehandedness, frugality, frugalness, gingerliness,
   good management, guardedness, hedge, hedging, heed, heedfulness,
   hesitation, husbandry, judiciousness, management, mindfulness,
   parsimoniousness, parsimony, pawkiness, prior consultation,
   providence, prudence, prudential administration, prudentialness,
   regard, regardfulness, safeness, safety first, slowness to act,
   solicitude, sparingness, tentativeness, thoroughness, thrift,
   thriftiness, tight purse strings, uncommunicativeness,
   unprecipitateness, unwastefulness