Good places to start

• All About Breast Cancer: American Cancer Society - ACS
• Breast Cancer: Cancer.Net (US)
• Breast Cancer: MedlinePlus (US)
• Breast Cancer: National Cancer Institute - NCI (US)
• Breast Cancer Navigation Map: Canadian Breast Cancer Foundation
• Breast Cancer, Now What?
• SharingStrength
• What is Breast Cancer?: Canadian Cancer Society

More breast cancer websites

• Breastcancer.org (US)
• Breast Cancer: University Health Network
• Canadian Breast Cancer Foundation
• Canadian Breast Cancer Network
• Imaginis (US)
• Johns Hopkins Breast Center (US)
• Living Beyond Breast Cancer (US)
• Ontario Breast Cancer Exchange Partnership
• Susan Love Research Foundation (US)

Inflammatory breast cancer websites

• Breast-Inflammatory Cancer: Cancer.Net (US)

Male breast cancer websites

• Breast Cancer-Male: Cancer.Net (US)
• Breast Cancer in Men: American Cancer Society - ACS
• Male Breast Cancer: Breastcancer.org (US)
• Male Breast Cancer: MedlinePlus (US)
• Male Breast Cancer: National Cancer Institute - NCI (US)
• Men with Breast Cancer: Canadian Breast Cancer Network - CBCN

Breast reconstruction websites

• Breast Reconstruction: Vancouver Coastal Health

Genetics and biology websites

• Biology of the Mammary Gland
• Genetics of Breast Cancer: Cancer.Net (US)
• Hereditary Breast and Ovarian Cancer Society of Alberta

Prevention and screening websites

• Breast Self Examination (BSE): Thunder Bay Breast Health Coalition
• Breast Self-Awareness: Susan G. Komen Breast Cancer Foundation
• Cancer Care Ontario Breast Screening
• Program on Breast Cancer and Environmental Risk Factors - BCERF: Cornell University

Support websites

• Breast Cancer Action Nova Scotia
• Breast Cancer Action Ottawa
• Breast Cancer, Now What?
• Caring Voices
• Inflammatory Breast Cancer Research Foundation
• Inflammatory Breast Cancer Support Group
• SharingStrength 
• Willow Breast Cancer Support Canada
• Young Survival Coalition

Decision tools

• Treatment Decision Tools: American Cancer Society - ACS
• Information on Mammography for Women Aged 40 and Older: A Decision Aid for Breast Cancer Screening in Canada: Public Health Agency of Canada
• Surgery Choices for Women with Early-Stage Breast Cancer: National Cancer Institute - NCI (US)

Practice guidelines

• Questions and Answers on Breast Cancer - A Guide for Women and their Physicians (scroll down the page)

Clinical trials

• National Surgical Adjuvant Breast and Bowel Project - NSABP (US)

Journal articles

• Abreast in the West
• Artemis - Johns Hopkins Breast Center e-journal