This study investigated the level of professional learning communities (PLCs), teachers' professional development (PD), and their relationship in Greek primary schools. This quantitative survey, which included 428 Greek public primary schools, yielded 674 and 571 responses regarding PLCs and PD, respectively. Hord's five PLC dimensions were measured using the Professional Learning Communities Assessment-Revised questionnaire. The National Staff Development Council's 12 standards/three PD dimensions were measured using the Standards Assessment Instrument. The findings revealed that primary schools function as PLCs, but at the second implementation level, thus not refining their culture or becoming mature PLCs. Teachers' PD experiences focused more on the content of their professional learning, whereas the standards of research, assessment, and learning communities presented lower averages. The non-significant, low-degree, and negative correlation between PLCs and PD indicates that, as schools do not provide sufficient job-embedded PD experiences, teachers' PD is based on individual initiatives rather than schools' needs/learning/development.