Purpose: A breast cancer diagnosis has a substantial economic impact. Study aims were to evaluate for inter-individual differences in cancer’s level of interference with employment and identify phenotypic and symptom characteristics associated with higher levels of interference. Methods: Patients (n = 387) were enrolled prior to breast cancer surgery and followed for 12 months. Interference with employment was measured using a 0 (no problem) to 10 (severe problem) numeric rating scale. Hierarchical linear modeling (HLM) was used to evaluate for inter-individual differences in trajectories of employment interference and characteristics associated with employment interference at enrollment and over 12 months. Results: Patients’ mean age was 55.0 (±11.7) years and the majority underwent breast conservation surgery (80.6%). Mean employment interference score was 3.2 (±3.7). Unconditional model for employment interference demonstrated a decreasing linear trend (−.076/month). Younger age, lower income, higher pain intensity, and having an axillary lymph node dissection were associated with higher pre-surgical interference scores. Having a sentinel lymph node biopsy was associated with ongoing employment interference scores. Higher sleep disturbance scores were associated with both initial and ongoing employment interference scores. Receipt of chemotherapy, use of complementary or alternative therapies, and re-excision or mastectomy following surgery were significant time varying covariates. Conclusion: This study is the first to use HLM to describe inter-individual differences in the trajectories of cancer’s interference with employment and associated factors prior to and for 12 months following breast cancer surgery. Patients with the identified risk factors warrant ongoing assessments of employment interference and appropriate referrals.